Self-billing inverts the normal VAT invoice. Instead of the supplier invoicing the customer, the customer raises the invoice on the supplier's behalf and sends it to them, along with the payment. It is standard practice in construction, recruitment, automotive and any sector where the buyer knows the quantity and the price before the seller does — and it is only valid where a written agreement exists first.
Why anyone does it
Self-billing exists because in some supply chains the customer holds the data. A main contractor measuring work completed on site knows the value before the subcontractor has written anything down. A manufacturer receiving components against a delivery schedule knows what arrived. An agency knows the hours the worker submitted through its own system.
Where that is true, self-billing removes an entire cycle of dispute: no invoice arrives with the wrong quantity, no query cycle, no payment delayed while a credit note is issued. Suppliers are paid faster and the buyer's purchase ledger reconciles by construction rather than by effort. The trade-off is that the buyer takes on the work and the VAT risk.
The conditions that make it valid
Self-billing is permitted without HMRC's prior approval, but it fails without the formalities:
- A written self-billing agreement with each supplier, made before any self-billed invoice is issued. The supplier must agree to accept invoices raised by the customer and — critically — not to issue VAT invoices of their own for the supplies covered;
- A start date and an expiry date. Both are required — an agreement left running indefinitely is not a valid self-billing agreement. The expiry can be tied to the term of the underlying contract between supplier and customer rather than a fixed calendar date. Reviewing agreements on a twelve-month cycle is sensible practice, but a review is not a substitute for a valid agreement with an expiry in it;
- Correct invoice content. A self-billed invoice must contain everything an ordinary VAT invoice contains, plus the supplier's name, address and VAT registration number, and must be clearly marked "self-billing";
- A copy to the supplier. The customer must send each self-billed invoice to the supplier and keep copies of all of them, along with the names, addresses and VAT numbers of every supplier who has agreed to the arrangement.
Fail any of these and the document is not a valid VAT invoice, which puts the customer's input tax recovery at risk on every transaction it covers — typically a large number of transactions discovered together.
The registration problem
The weakness of self-billing is that the customer is asserting the supplier's VAT status without controlling it. If a supplier deregisters, or has their registration cancelled, and the customer keeps raising self-billed invoices showing VAT, the customer is reclaiming input tax that was never properly charged. HMRC will assess it, and the fact that the supplier never mentioned the change is not a defence.
The controls that address this are unexciting and effective: verify each supplier's VAT number at the point the agreement is signed, re-verify periodically — HMRC's online checker and the EU equivalent make this a minute's work — and require suppliers to notify any change in status as a term of the agreement. Businesses running hundreds of self-billing arrangements should automate the re-verification rather than sample it.
A related point: where the supplier is not VAT registered at all, self-billing can still be used, but no VAT may be shown. Recruitment and construction chains that self-bill sole traders get this wrong in both directions — charging VAT on supplies from unregistered workers, and omitting it from registered ones.
Where it interacts with other rules
Two overlaps deserve attention. In construction, self-billing sits alongside the domestic reverse charge: where the reverse charge applies, the self-billed invoice must reflect it, showing no VAT charged and a statement that the customer accounts for it. Getting the self-billing right and the reverse charge wrong produces an invoice that is doubly defective.
In construction again, self-billing frequently coexists with the construction industry scheme, where the contractor is already calculating and deducting tax from payments — which makes self-billing a natural fit operationally, and makes the consequences of a systemic error larger, because one mistake replicates across every subcontractor and every month.
Running it properly
For the customer: hold a signed agreement per supplier, review them on a schedule, verify VAT numbers on a schedule, mark every document "self-billing", send copies, and keep the supplier register. For the supplier: read what you have agreed to, stop issuing your own invoices for those supplies to avoid duplication, check the self-billed invoices rather than assuming they are right, and tell the customer immediately if your VAT status changes — because the liability for getting it wrong will find its way back to the party that caused it.
Errors found later are corrected through the ordinary route, and the thresholds and disclosure quality then determine the cost — the mechanics of which we set out in our guide to correcting a VAT error.
Acumon reviews self-billing arrangements as part of VAT compliance and VAT health check work, including the supplier verification controls that most arrangements are missing. If you self-bill a large supplier base and have never re-checked their VAT numbers, that is where the exposure is.