How to avoid common VAT reverse charge mistakes when invoicing main contractors

If you are a VAT-registered subcontractor billing a VAT-registered main contractor for CIS-reportable construction services, you should usually be applying the domestic reverse charge rather than adding VAT to the invoice. The customer accounts for the VAT instead. The expensive mistakes are charging VAT when the reverse charge applies, treating a contractor as an end user without written notification, and forgetting the box 1 entry when you are the contractor receiving the invoice. The rules have been in place since March 2021, and HMRC’s early light-touch period is long over.

The rules themselves have not changed. Enforcement and software checks have.

The four checks before you invoice

Run through these every time. Not once a year.

That last one catches people out constantly. End user status does not switch the reverse charge off by itself. The customer has to tell you in writing, and you need to keep that notification with your VAT records. A tier one contractor might be an end user on one project and part of an onward supply chain on the next, so a single blanket declaration from three years ago is not enough evidence for every job.

What the invoice has to say

The invoice shows no VAT to pay, but it cannot simply be silent. It needs a statement that the reverse charge applies and either the VAT amount the customer must account for, or the rate that would have applied. Wording along these lines works:

Reverse charge: customer to account for VAT to HMRC. VAT Act 1994 section 55A applies. VAT rate 20%, £1,680.

If you leave that off, the contractor’s finance team will very likely reject the invoice, and payment can slip by a month. We have seen a small groundworks firm sit on £60,000 of unpaid applications for exactly that reason.

The 5% disregard and mixed invoices

The 5% disregard is useful, but it is often misquoted. If there is a single supply under a contract and the reverse charge element is 5% or less of the total value, the parties can agree from the start to ignore that minor element and apply normal VAT rules. It is optional, not compulsory, and it should not be calculated casually invoice by invoice after the event.

Where a single supply includes reverse charge work above that level, the reverse charge will usually apply to the whole supply. Genuine separate supplies may still need separate VAT treatment, but do not split an invoice artificially just to make the VAT answer look cleaner.

Errors on the return side

Getting the invoice right is only half of it. Both parties then have to report it properly.

Missing the box 1 entry as the customer is the single most common error HMRC finds. For a fully taxable business the net effect is often nil, which is precisely why nobody notices until an inspection. Cash accounting cannot be used for reverse charge supplies, and the flat rate scheme often stops making sense once most of your sales carry no VAT.

Cash flow is the other consequence worth planning for. If most of your output VAT disappears, you may move into repayment, and regular refunds change how you forecast. It is worth periodically taking a look at your HMRC VAT account to check nothing is sitting unallocated. Recording it correctly in Xero with the right tax rate applied at source saves a great deal of unpicking later.

HMRC’s guidance on the domestic reverse charge sets out the detail if you want to check an unusual case.

Where property work complicates things

Contractors working for managing agents or landlords hit a particular wrinkle. Where the customer is a property owner having work done on its own building, that customer is usually an end user, provided it gives the right written notification, so normal VAT applies. Where the agent is passing the cost down through a service charge or acting in a chain of onward construction supplies, the position needs checking rather than assuming.

Agents on the other side of that invoice should also make sure the treatment matches their ledgers, which our guide to commercial property management accounting covers, along with our service charge accounting guide. VAT errors on major works tend to surface when year-end service charge statements are prepared, by which point the invoice may already be a year old.

Keep the underlying records clean too. If you trade through a company, our profit and loss filing checklist is worth a look, and sole traders under quarterly reporting should read our note on MTD and agent access.

FAQs

Do I charge VAT to a main contractor?

Not usually, if you are VAT registered, the work is CIS-reportable and standard or reduced rated, and the contractor is VAT and CIS registered. If the contractor has not notified you in writing that it is an end user or intermediary supplier, the reverse charge usually applies and you show no VAT to pay.

What if I have been charging VAT by mistake?

Correct it. You may need to issue credit notes, reissue invoices and adjust VAT returns. The contractor should not reclaim VAT that should not have been charged, so the error will usually need to be unwound.

Does the reverse charge apply to materials?

Yes, where materials are supplied as part of a construction service covered by the rules. A supply of materials alone, with no construction service, is outside the construction reverse charge.

Get a second look at your VAT treatment

If you are unsure whether your invoices are right, a review now is cheaper than an assessment later. FHP Accounting handles VAT returns, bookkeeping, company tax returns and annual statutory accounts, and can run the whole function for you through our outsourced finance department. Contact our team and we will check your reverse charge position across a sample of recent invoices.

Kellee Quigley

I lead FHP Accounting, an accountancy practice specialising in Commercial and Residential Property Accounting. Our goal is to make the administration of running property portfolios easier for landlords, managers, and investors — allowing you to focus on what you do best, while we take care of everything behind the scenes.