The most common self-billing mistakes are raising invoices without a valid agreement, showing VAT for a supplier who isn’t (or is no longer) VAT-registered, letting agreements lapse, and applying the reverse charge incorrectly. Each is avoidable with current supplier records and software that applies the right treatment.
Key points
- Never self-bill without a current written agreement.
- Keep supplier VAT status and numbers up to date.
- Apply the reverse charge only where it’s actually due.
- Track agreement review dates.
Invoicing without a valid agreement
You can’t self-bill a supplier until a written agreement is in place — and you must stop if it lapses. Track review dates so agreements don’t expire unnoticed.
Stale VAT status
Showing VAT for a supplier who has deregistered, or not showing it once they register, both cause VAT errors. Keep each supplier’s VAT status and number current.
Wrong reverse-charge treatment
Applying the CIS reverse charge outside construction, or missing it where it’s due, is a frequent error. The reverse charge is construction-specific; use standard VAT elsewhere.
This is general information, not tax advice — confirm your own position with your accountant or HMRC (see VAT Notice 700/62 on self-billing).