Best Invoicing App for UK Tradespeople 2026: HMRC-Compliant, CIS-Ready, Trade-Specific

Q: What CIS deduction rate applies if a contractor has not verified me?

If a CIS contractor has not yet verified you with HMRC, they must deduct 30% from your gross labour payments instead of the standard 20% verified rate. Once they verify you and HMRC confirms your registration, the rate drops to 20% (or 0% if you hold gross payment status). You cannot receive the 20% rate until the contractor completes the HMRC verification call or online check. Always ask new contractors to verify you before your first invoice to avoid the higher 30% deduction.

Q: When does domestic reverse charge apply instead of standard VAT?

The CIS domestic reverse charge (DRC) applies when: (1) both the subcontractor and the contractor are VAT-registered; (2) the work is within the scope of CIS (construction services); and (3) the contractor is not the end user — they are supplying those construction services onward. It does NOT apply to supplies directly to a domestic homeowner or to a business using the building themselves (end users). When DRC applies, the subcontractor does not charge VAT — the contractor self-accounts for it to HMRC. The invoice must state 'Reverse charge — customer to account for VAT to HMRC at 20%'.

Q: Do I need to split labour and materials on every invoice?

You must split labour and materials separately on any CIS subcontract invoice. This is because CIS deductions apply only to the labour element — the contractor must be able to identify each element to calculate the correct deduction. If you do not split them, the contractor is required to treat the entire invoice as labour and deduct CIS from the full amount, costing you more tax. For non-CIS domestic jobs there is no legal requirement to split them, but doing so is good practice for transparency and dispute prevention.

Q: How do I add a late payment clause to my invoices?

Under the Late Payment of Commercial Debts (Interest) Act 1998, you are automatically entitled to claim 8% above the Bank of England base rate on overdue business-to-business invoices, plus a fixed compensation charge (£40 for debts under £1,000, £70 for £1,000–£9,999, £100 for £10,000 and above). You do not need to include a clause — the right exists in law. However, adding the following wording to your invoice footer reinforces it and deters late payment: 'We reserve the right to charge statutory interest and compensation under the Late Payment of Commercial Debts (Interest) Act 1998 on overdue invoices.'

Written by Tom Ellis · Senior Trades Editor

Last updated: July 2026

Quick answers

Best overall for sole traders: Sleepless Tradesman — free to start, UK-built, handles CIS deductions and domestic reverse charge VAT natively.
Legally required fields: 7 fields for non-VAT sole traders; 4 additional fields if VAT-registered; 3 more if you are a CIS subcontractor — details in the compliance table below.
CIS deduction rate: 20% from verified subcontractors' labour; 30% from unverified; 0% with gross payment status. Materials are never deducted.
Late payment: You are automatically entitled to 8% above base rate plus £40–£100 fixed compensation on overdue B2B invoices under the 1998 Act — no clause needed, but adding one deters late payers.

Most invoicing guides for tradespeople focus on which app has the best interface. This guide focuses on something more consequential: getting paid correctly while staying fully HMRC-compliant. For UK tradespeople, these are not the same thing. A gas engineer who omits their Gas Safe number from an invoice is in breach of statutory regulations regardless of how polished the invoice looks. A CIS subcontractor who fails to split labour and materials correctly will either overpay or underpay tax — and HMRC penalties follow. A VAT-registered electrician on a commercial subcontract who charges VAT instead of applying the domestic reverse charge has issued a non-compliant invoice that the contractor cannot recover.

This guide covers the legal requirements for UK tradesman invoices from the ground up, the six real invoicing scenarios tradespeople face and how each one works, a compliance-focused app comparison, trade-specific invoice requirements by trade, and the late payment rights most tradespeople never use. The app recommendations follow from those compliance requirements — not the other way around.

What Makes a UK Tradesman Invoice Legally Valid?

HMRC does not prescribe a single invoice template, but it does prescribe the minimum information that must appear on an invoice depending on your VAT status and business structure. Missing required fields can make a VAT invoice invalid (meaning the customer cannot reclaim the VAT), create disputes about payment terms, and expose you to penalties. The table below sets out the three tiers of required information.

Field	Sole trader (no VAT)	VAT-registered	CIS subcontractor
Your business name and address	Required	Required	Required
Unique sequential invoice number	Required	Required	Required
Invoice date	Required	Required	Required
Payment due date	Required	Required	Required
Customer name and address	Required	Required	Required
Clear description of works	Required	Required	Required
Total amount due	Required	Required	Required
Your VAT registration number	—	Required	Required if VAT-registered
VAT rate applied (or DRC wording)	—	Required	Required
VAT amount charged	—	Required	Required (or £0 if DRC)
Tax point date (if different from invoice date)	—	Required	Required
Your UTR (Unique Taxpayer Reference)	—	—	Required
Labour amount (separate line)	—	—	Required
Materials amount (separate line)	—	—	Required
CIS deduction rate and amount	—	—	Required
Net amount payable (after CIS deduction)	—	—	Required

Simplified VAT invoices.If the total invoice is under £250 including VAT, you may issue a simplified invoice that omits the customer's name and address, itemised VAT, and the tax point — but it must still carry your VAT number, the rate applied, and a gross total. Most tradespeople should use full invoices regardless, because simplified invoices cannot be used if the customer wants to reclaim input VAT.

Limited companies. If you trade through a limited company, the invoice must also show your company registered name (not just the trading name), company registration number, and registered office address. These are legal requirements under the Companies Act 2006 and apply on all business correspondence, not just invoices.

Why Generic Invoicing Apps Fail Tradespeople

Wave, Zoho Invoice, Invoice Ninja and similar general-purpose invoicing tools are built for freelancers, consultants and small retail businesses. They handle the basics — sequential numbering, VAT, payment terms — but stop well short of what UK construction trades actually need. The gaps are not cosmetic.

No CIS deduction calculation

Generic apps do not know what CIS is. They cannot split labour from materials, apply a 20% or 30% deduction to the labour line only, calculate the net payable, or generate the deduction statement the contractor needs. You end up doing this on a spreadsheet, which creates errors and delays.

No domestic reverse charge VAT handling

The DRC rule introduced in March 2021 is one of the most misapplied VAT rules in UK construction. Generic apps apply standard 20% VAT even when DRC should apply, or provide no way to issue a zero-VAT invoice with the correct statutory wording. A subcontractor who charges VAT on a DRC supply has issued a non-compliant invoice — the contractor will bounce it back, delaying payment.

No trade-specific registration number fields

There is no field in a generic invoicing app for a Gas Safe registration number, NICEIC membership, NAPIT number, or WaterSafe approval. You can add these to a notes field, but they do not appear in the correct legal position on the invoice, are easy to forget, and are not validated against your registration records.

No trade-specific line item templates

Tradespeople regularly invoice for items that general apps have never heard of: call-out fees, out-of-hours uplifts, materials markup percentages, waste disposal and skip hire, scaffold standing time, interim valuations with retention, and stage payments. Without preset trade line items, you retype these from scratch on every job — and risk inconsistency that fuels disputes.

Not built for MTD for Income Tax (ITSA)

Making Tax Digital for Income Tax Self Assessment becomes mandatory for sole traders with income over £20,000 from April 2026. Generic invoicing apps may handle MTD for VAT, but most do not maintain the HMRC-required digital income and expense records that ITSA demands, and they cannot submit quarterly updates directly to HMRC. You end up exporting data to another system — introducing the errors you were trying to avoid.

The 6 Invoicing Scenarios UK Tradespeople Face

Not every job is invoiced the same way. The correct invoice structure depends on your VAT status, the customer's status, the nature of the work, and whether CIS applies. Here are the six scenarios you are most likely to encounter and exactly what each invoice must contain.

Standard sole trader job — no VAT

Applies when: You are below the £90,000 VAT threshold and not voluntarily registered. Typical for sole traders in the early years or those deliberately staying below the threshold.

Your name or trading name and contact address
Unique invoice number (sequential — never reuse)
Invoice date and payment due date (default 30 days B2B)
Customer full name and site or billing address
Description of works — specific enough to match the job (include postcode of works)
Labour hours or day rate and total, materials at cost or as agreed
Total amount payable in pounds
Bank details: sort code, account number, account name
Do not add a VAT number, VAT rate, or VAT amount — you are not registered

Common mistake: Adding “VAT: £0” or “No VAT charged” with a fake VAT number to look more credible. This is a criminal offence under the Value Added Tax Act 1994.

VAT-registered tradesperson — standard domestic job

Applies when: You are VAT-registered and doing a standard job for a domestic homeowner or a business that is the end user of the building. Standard 20% VAT applies in most cases; 5% for qualifying energy-saving measures.

All fields from scenario 1, plus:
Your VAT registration number (GB followed by 9 digits)
Tax point date (usually the invoice date, or the date of supply if earlier)
Net amount for each line item (ex-VAT)
VAT rate for each line (20%, 5%, or 0% with reason)
Total VAT amount charged
Gross total including VAT

Energy-saving materials: If supplying and installing qualifying items (solar panels, heat pumps, insulation, draught-proofing) for a residential customer, the 5% reduced rate applies to both the materials and the installation labour. The invoice must state the 5% rate against those specific lines — a blanket 20% invoice on an eligible job is both overcharging the customer and potentially creating a VAT error.

CIS subcontractor invoice to contractor

Applies when: You are working as a subcontractor for a main contractor on a construction project and are registered under CIS. The domestic reverse charge does NOT apply (either you or the contractor is not VAT-registered, or the contractor is an end user).

Your UTR (Unique Taxpayer Reference — 10 digits)
Contractor's name, address and CIS contractor reference or purchase order number
Labour amount (gross, before CIS deduction) — stated clearly as a separate line
Materials amount (separate line — no CIS deduction applies to materials)
CIS deduction rate: 20% if verified, 30% if not yet verified by this contractor
CIS deduction amount (applied to labour only, not materials)
Net amount payable (labour + materials minus CIS deduction)
If VAT-registered: VAT at 20% on the full gross amount (labour + materials) before the CIS deduction — VAT is on gross, not net

Critical point on VAT in CIS invoices: The CIS deduction is made from your gross payment but does not reduce the VAT base. If your gross labour + materials is £1,000 and the CIS deduction is £200, the contractor pays you £800 — but the VAT (if applicable) is still calculated on £1,000 and paid in full.

Domestic reverse charge (DRC) job

Applies when: You are a VAT-registered subcontractor supplying construction services to a VAT-registered main contractor, and the contractor is not the end user of the building (they are supplying those services onward). Introduced 1 March 2021.

All CIS subcontractor fields above (UTR, labour/materials split, CIS deduction)
Your VAT registration number
The exact statutory wording: “Reverse charge — customer to account for VAT to HMRC at 20%”
The VAT amount that would have applied (shown for reference, but NOT added to the payable total)
Payable total = labour + materials minus CIS deduction (VAT is excluded — contractor self-accounts)
Do NOT include VAT in your invoice total — this is the most common error

End user exception: DRC does not apply if the contractor is the end user — for example, a property developer building a house they will live in, or a business building their own premises. End users must confirm their status to you in writing. If they do not, and you apply standard VAT when DRC should apply, both parties face compliance issues.

Emergency callout invoice

Applies when: You respond to an emergency — burst pipe, boiler breakdown, power failure, roof leak in a storm — where the job scope was not agreed in advance and you may be charging premium rates. These invoices are most commonly disputed, so line-item clarity is essential.

Callout fee — stated as a fixed charge for attending, separate from labour
Out-of-hours uplift — if applicable, state the standard rate and the uplift percentage or fixed premium (e.g. “Out-of-hours rate: 50% uplift on standard labour”)
Travel time and distance — if you charge for travel, state the rate per mile or per hour and the distance/time incurred
Labour time on site — start and end time recorded (ideally signed by customer), hourly rate, total hours, total labour charge
Materials used — itemised by part name, quantity and unit price; do not lump materials into a single “parts” figure if the job value is significant
Waste disposal charge — if you removed waste, state the charge explicitly rather than absorbing it silently
Any temporary repair note — if a temporary fix was applied pending a permanent repair, state this clearly so the scope of the emergency invoice is bounded

Stage payment and retention invoice

Applies when: A large project is billed in stages — common for builders, roofers, groundworkers and any trade on a multi-week or multi-month contract. Retention clauses are standard on commercial contracts and increasingly used on larger domestic jobs.

Interim valuation number (e.g. “Valuation 3 of 5”) — sequential across the project
Contract reference or project name — so both parties can track against the agreed contract
Gross value of work completed to this valuation date
Less: amounts previously certified and paid (running total)
Value of work this invoice: gross completed minus previously paid
Retention deducted: state the retention percentage (commonly 5%), the amount held on this valuation, and the cumulative retention held
Net amount payable on this invoice (work done this period minus retention)
Retention release conditions: state clearly when retention is released (e.g. “50% on practical completion, 50% at end of 6-month defects liability period”)
Any contra-charges or set-offs applied — must be itemised and agreed; you can dispute invalid contra-charges

Sleepless Tradesman

Quote, invoice and manage jobs — all in one app

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App Comparison: Compliance Features That Matter

Rated on the six compliance criteria that actually matter for UK tradespeople — not general invoicing features that every app has. Apps that do not natively handle a feature score a dash, even if a workaround exists, because a manual workaround is where errors happen.

App	CIS deduction	VAT / DRC	Mobile invoicing	Trade line items	Payment link	Auto payment chase
Sleepless Tradesman	Yes (native)	Yes + DRC	Yes	Yes	Yes	Yes (Pro)
FreeAgent	Partial	VAT only	Yes	No	Yes	Yes
QuickBooks	Partial	VAT + partial DRC	Yes	No	Yes	Yes
Xero	Partial	VAT + partial DRC	Yes	No	Yes	Yes
Tradify	Yes (native)	VAT + DRC	Yes	Good	Partial	Partial
Sage 50	Yes (native)	VAT + DRC	Limited	No	Yes	Yes

Sleepless Tradesman — free + £9.99/mo Pro

Built from the ground up for UK sole traders, with CIS deduction lines, domestic reverse charge wording, trade-specific invoice templates (callout fees, emergency uplifts, labour/materials splits), and MTD for both VAT and ITSA. The free tier is fully functional for invoicing. Pro adds automated payment reminders, expense tracking with receipt capture, and full ITSA digital records. Because it is UK-built, all compliance defaults — VAT rates, CIS rules, MTD requirements — are correct without configuration.

FreeAgent — £19–29/mo (free with NatWest/RBS/Ulster Bank)

Strong UK accounting platform popular with sole traders and small businesses. Excellent MTD for VAT and ITSA support, professional invoicing, and good expense tracking. CIS support is partial — it can generate CIS deduction statements but the labour/materials split and deduction line items require manual setup. No native trade-specific line item templates. Good for tradespeople who primarily invoice domestic end users and need accounting more than CIS compliance.

QuickBooks — £14–35/mo

QuickBooks has added CIS functionality for UK users, including subcontractor verification status and deduction calculations. DRC VAT handling exists but requires correct configuration by an accountant — it does not auto-detect when DRC applies based on the supply chain. Strong mobile app, good receipt capture, and robust reporting. Better for tradespeople who already use QuickBooks for accounting than as a pure invoicing switch.

Xero — £16–47/mo

Xero's UK product includes CIS modules and DRC VAT codes, but as with QuickBooks, these require correct setup. Out of the box, Xero does not automatically apply DRC — you or your accountant must configure the correct tax codes. Once set up correctly, it is powerful and its ecosystem of add-ons (Tradify, ServiceM8, simPRO) makes it attractive for larger trade businesses. Expensive for a sole trader using only invoicing.

Tradify — £39–49/mo

A field service management platform with good UK trade focus, Tradify includes CIS and DRC handling alongside job scheduling, quoting and invoicing. Better suited to businesses with multiple tradespeople that need scheduling alongside invoicing. Overkill — and expensive — for a sole trader whose primary need is compliant invoicing.

Sage 50 — £30–85/mo

Sage 50 is desktop-first accounting software with full CIS contractor and subcontractor functionality, comprehensive VAT including DRC, and strong payroll integration. It is the traditional choice for established contractors with turnover above £100,000 and an in-house bookkeeper. The mobile experience is limited and it is significantly over-specified — and expensive — for the typical sole-trader tradesperson.

Trade-Specific Invoice Requirements

Beyond the universal HMRC fields, every regulated trade has additional information that must — or should by strong professional practice — appear on invoices. These are the fields that generic apps do not know about and that generic invoicing advice never covers. Get them wrong and you face regulatory complaints, insurance disputes, and customers who legitimately withhold payment pending a compliant invoice.

Electricians

Electrical installation work notifiable under Part P of the Building Regulations must be carried out by an approved competent person scheme member — NICEIC, NAPIT, ELECSA, or NICEIC-registered contractors. Part P notifiable work includes new circuits, consumer unit (fuseboard) replacements, and work in special locations (bathrooms, outdoors, swimming pools). The scheme registration number is not just good practice — it is the evidence that the work was legally self-certified.

NICEIC or NAPIT registration number — must appear on every invoice and every certificate issued for Part P notifiable work. Customers need this number to confirm the work was legally carried out under a competent person scheme.
Electrical Installation Certificate (EIC) or Minor Works Certificate (MWC) reference number — tie the invoice to the certificate number. Both documents are required for Building Regulations compliance and for the property's future sale; the invoice is the financial record and the certificate is the technical record.
EICR reference number — for condition report jobs, cross-reference the Electrical Installation Condition Report number on the invoice. Landlords in particular need this for licensing and compliance purposes.
Address of electrical installation — state the full address of the property where works were carried out, even if it differs from the invoice billing address. Critical for multi-property landlords and commercial clients.
5% reduced VAT rate notation — for qualifying energy-saving materials (solar panels, battery storage, heat pump components), state the 5% rate against those specific lines. HMRC requires evidence of the reduced rate; a blanket 20% invoice on eligible items is an error that the customer may dispute and HMRC may challenge.
CIS domestic reverse charge wording — for commercial subcontract work where both parties are VAT-registered and DRC applies: “Reverse charge — customer to account for VAT to HMRC at 20%.”

Full guide: Best invoicing app for electricians UK →

Gas Engineers

Gas engineers face the most prescriptive legal requirements of any trade when it comes to invoicing. Under the Gas Safety (Installation and Use) Regulations 1998, it is a criminal offence to carry out gas work without Gas Safe registration. That registration number must appear on all customer-facing paperwork — every invoice, every quote, every letter. This is not an industry guideline; it is a statutory requirement enforced by the Health and Safety Executive and Gas Safe Register itself. Customers can verify any registered engineer's number at gassaferegister.co.uk.

Gas Safe registration number — mandatory on every invoice for any job that involves gas appliances, pipework or fittings. No exceptions. Omission is a regulatory breach regardless of whether the work itself was competent.
CP12 (Landlord Gas Safety Record) reference number — for any job where a landlord gas safety certificate was issued, note the unique CP12 certificate number on the invoice. Landlords are legally required to keep records; your invoice is part of their compliance documentation.
Appliance make, model and serial number — for any work on a specific appliance (boiler service, repair, replacement), include all three in the job description. This bounds the scope of your invoice and protects you if the appliance subsequently fails and the customer claims the fault was pre-existing or caused by your work.
Annual service record reference — for boiler servicing, cross-reference the service record number so the customer has a continuous maintenance history linked to payment records. Useful for lease agreements and boiler warranty claims.
Gas tightness test result notation — where a gas tightness test was carried out (required after any work on pipework), note the result (Pass) in the job description. This is evidential if a subsequent gas leak is attributed to your work.

Full guide: Best app for gas engineers UK →

Builders and CIS Subcontractors

Builders face the most complex invoicing of any trade, often operating simultaneously as CIS contractors (paying their own subcontractors) and CIS subcontractors (receiving payment from a developer or main contractor). Interim valuations, retention clauses, domestic reverse charge, and planning permission references all appear on building invoices that would not exist in any other trade.

UTR number — required on every CIS subcontract invoice. This is how the contractor verifies your deduction rate with HMRC. Without it, they must apply 30% unverified deduction.
Labour / materials split — mandatory on CIS invoices. Labour is subject to CIS deduction; materials are not. If you bundle them, the contractor is required by HMRC guidance to treat the entire invoice as labour — costing you more tax.
CIS deduction line — show the gross labour, the deduction rate, the deduction amount, and the net payable. This becomes the basis for your monthly CIS deduction statement from the contractor.
Planning permission or prior approval reference — for notifiable building work, include the local authority planning reference number in the job description. This ties the invoice to the legal framework under which the work was carried out.
Retention terms — if retention applies, state the percentage (typically 5%), the retention amount held on this valuation, cumulative retention held, and the conditions and timeline for release.
Structural warranty reference — for new-build or major extension work covered by an NHBC Buildmark or Premier Guarantee warranty, note the warranty registration number. The customer needs it to register the warranty in their name.

Plumbers

Plumbing does not have a universal Part P equivalent — there is no single national mandatory registration scheme for plumbers in England (though Scotland and Northern Ireland have different rules). However, WaterSafe membership (the approved contractor scheme overseen by the Water Regulations UK Committee) is increasingly required by local water authorities on commercial and new-build work involving notifiable plumbing. If you are also Gas Safe registered and carry gas work on any invoice, the Gas Safe requirements above apply to those specific jobs.

WaterSafe approval number — include on all commercial and new-build invoices where Building Regulations notification applies, and on any invoice where you want to demonstrate competent person scheme approval to a customer.
Location of isolation valve or stop cock — for emergency plumbing jobs (burst pipe, flood), note the location of the stop cock or isolation valve that was used, and its current state (open or closed). This protects you if there is a subsequent flood claim and your scope of work is disputed.
WRAS approval references — for commercial jobs involving water fittings that must be WRAS-approved, note the product approval reference in the materials schedule where the client has supplied fittings, to document that compliant fittings were specified.
Labour / materials split — required for CIS subcontract work (commercial sites, new-build developments). Particularly important on large commercial plumbing contracts where materials can constitute 60–70% of the invoice value.
Pressure test result — for pipework installations, note whether a pressure test was carried out and the result. This evidential record is essential if a leak subsequently occurs and the customer claims it was due to your installation.

Roofers

Roofing is consistently ranked among the most fraud-affected trades in the UK — HMRC, Trading Standards, and insurers all flag it. Legitimate roofers can differentiate themselves through invoice detail: membership numbers, manufacturer guarantee references, materials specifications, and insurance claim references. For storm damage and insurance-funded work, the invoice must carry the insurer's reference or the insurer's accounts payable team will reject it.

NFRC membership number — the National Federation of Roofing Contractors membership number is required for some commercial framework contracts and provides assurance to domestic customers that the roofer is vetted and insured.
Insurance claim reference number — for any storm or accidental damage repair funded by a home or commercial insurer, the insurer's claim reference must appear on your invoice before they will process payment. Obtaining this reference before starting work, not after, avoids invoice rejection delays.
Flat roofing guarantee reference — manufacturer-backed guarantees for felt, GRP, EPDM or liquid roofing systems (Firestone, IKO, Sika, Bauder) come with a reference number once the installer registers the job. Include this on the invoice so the customer can register their guarantee independently.
Materials specification — specify roofing materials to BS standards or named products (e.g. “Marley Eternit Acme clay plain tile, 65 per m², fixed to BS 5534”). This prevents disputes where a customer expected a premium product and received a budget alternative.
Scaffold supply reference — if scaffold was hired from a third party and charged to the customer, note the hire company's name, the scaffold reference, the hire period, and the standing day rate if applicable. Scaffold disputes are a common cause of retention arguments on roofing jobs.

Late Payment Law: Rights Most Tradespeople Never Use

The Late Payment of Commercial Debts (Interest) Act 1998, as substantially amended by the Late Payment of Commercial Debts Regulations 2013, gives UK businesses automatic rights to charge interest and compensation on overdue invoices — without any clause in your contract. These rights exist by operation of law in every B2B transaction in England, Wales and Scotland. Most tradespeople are unaware they can exercise them; many contractors rely on that ignorance to delay payment.

Element	Detail
Statutory interest rate	8% per annum above the Bank of England base rate, calculated on the overdue amount from the day after the payment due date
Fixed compensation — debt under £1,000	£40 per overdue invoice, automatic, no need to invoice separately
Fixed compensation — debt £1,000 to £9,999	£70 per overdue invoice
Fixed compensation — debt £10,000 and above	£100 per overdue invoice
Reasonable debt recovery costs	If the fixed compensation does not cover your reasonable costs of recovering the debt, you can also claim the difference
B2C (domestic customers)	The Act applies to B2B transactions. For domestic consumer debts, different rules apply under consumer contract regulations — statutory interest still applies but through a different mechanism
Contractual override	You can agree different interest rates or payment terms by contract, but a contractual rate lower than the statutory rate is unenforceable
When does interest start?	The day after the contractual due date (e.g. day 31 if terms are 30 days), or if no terms were agreed, the day after 30 days from when the invoice was delivered

How to exercise your rights. You do not need a clause in your contract — the right is statutory. However, adding the following wording to every invoice footer serves two practical purposes: it reminds the customer of the law (deterrence) and it evidences that the right was not waived. Include this on the face of the invoice under payment terms:

“We reserve the right to charge statutory interest at 8% above the Bank of England base rate on overdue invoices, together with fixed compensation and reasonable recovery costs, under the Late Payment of Commercial Debts (Interest) Act 1998.”

Issuing a late payment notice. When an invoice becomes overdue, send a written late payment notice (email is sufficient) stating: the original invoice number and date; the amount overdue; the number of days overdue; the statutory interest accruing per day (calculate as: overdue amount × (0.08 + base rate) ÷ 365); and the fixed compensation amount. This creates a paper trail and is often sufficient to trigger payment without further action.

B2C (domestic customer) jobs. The 1998 Act applies to business-to-business debts. For domestic consumer customers, you cannot charge 8% statutory interest under this Act — however, if your contract included payment terms, interest at the agreed rate can be claimed. For domestic jobs where a customer simply refuses to pay, the small claims court (claims under £10,000) or a county court judgment are the practical routes. Invoicing software that generates a clear audit trail — timestamped invoices, delivery confirmations, chaser records — is essential evidence in any court claim.

Frequently Asked Questions

Does a sole trader invoice need a VAT number?

No — if you are not VAT registered, you must not charge VAT and must not show a VAT number on your invoice. Only businesses registered for VAT (those above the £90,000 threshold or voluntarily registered) may charge VAT. Adding a fake VAT number — even just to look more professional — is a criminal offence under the Value Added Tax Act 1994. If you are VAT registered, your GB VAT number (9 digits) must appear on every full VAT invoice you issue.

What CIS deduction rate applies if a contractor has not verified me?

If a CIS contractor has not yet verified your registration with HMRC, they are required to deduct 30% from your gross labour payments — not the standard 20% verified rate. Once they verify you online via HMRC's CIS service and HMRC confirms your registration, the rate drops to 20%. If you hold gross payment status (earned by demonstrating a good tax compliance record), the deduction rate is 0%. Always ask new main contractors to verify your CIS status before submitting your first invoice — it prevents the higher 30% deduction and means you are not waiting for a tax refund at year end.

When does domestic reverse charge apply instead of standard VAT?

The CIS domestic reverse charge (DRC) applies when three conditions are all met: (1) you as the subcontractor are VAT-registered; (2) the contractor you are supplying is VAT-registered; and (3) the contractor is not the end user of the building — they are supplying those construction services onward (e.g. to a developer, to an end client). If the contractor is an end user (a business using the building itself, or a domestic homeowner), DRC does not apply and you charge standard VAT. The contractor must confirm their end-user status to you in writing; without that confirmation, you should assume DRC applies to avoid the more serious error of charging VAT when you should not.

Do I need to split labour and materials on every invoice?

You are legally required to split labour and materials on any CIS subcontract invoice. This is because CIS deductions apply only to the labour element — the contractor needs to identify materials separately to apply the deduction correctly. If you do not split them, HMRC guidance requires the contractor to treat the entire invoice as labour, applying CIS to the full amount including materials — which costs you more tax than necessary. For non-CIS domestic consumer invoices there is no legal requirement to split them, but doing so is strongly recommended: it is transparent, prevents “why are you charging me for parts?” disputes, and makes your records cleaner for self-assessment.

How do I add a late payment clause to my invoices?

You do not strictly need to add a clause — your right to claim statutory interest and fixed compensation under the Late Payment of Commercial Debts (Interest) Act 1998 exists automatically in every B2B transaction. However, adding the recommended wording to your invoice footer reinforces the right, reminds customers of the consequences of late payment, and ensures there is no argument about whether the right was waived. Recommended wording: “We reserve the right to charge statutory interest at 8% above the Bank of England base rate on overdue invoices, together with fixed compensation and reasonable recovery costs, under the Late Payment of Commercial Debts (Interest) Act 1998.”

Is my Gas Safe number required on invoices for work that is not gas-related?

Your Gas Safe number is only legally required on invoices for work that involves gas appliances, pipework or fittings. If you issue a purely plumbing invoice — replacing a tap, unblocking a drain — that does not touch a gas installation, the Gas Safe number is not mandated on that specific invoice. However, many gas engineers include it on all customer-facing documents as standard practice. The critical rule: any invoice that relates to any gas work whatsoever must include your Gas Safe registration number. Omitting it from a gas job invoice is a breach of the Gas Safety (Installation and Use) Regulations 1998, regardless of how well the work was carried out.