Usually a settings issue rather than a calculation one — and quick to put right once you know where to look.
16 August 2026 · 4 min read
VAT errors on customer paperwork are worth fixing promptly — they are visible, they undermine confidence, and they cause problems at return time.
If you are VAT registered but no VAT appears, your VAT registration almost certainly is not switched on in settings. Add your registration and rate, and new documents will include it.
The reverse problem, and more serious — charging VAT you are not registered for is not allowed. Turn the setting off and correct any documents already issued.
Most trade work is standard-rated, but some construction work qualifies for reduced or zero rating, and there are special rules for new builds and certain renovations. If your work regularly falls outside 20%, check with your accountant and set the rate deliberately rather than assuming.
A price typed as inclusive of VAT and then treated as exclusive produces a total that looks 20% too high. Be consistent about which you are quoting — and say which on the document.
Reissue the corrected quote, or for an invoice, issue a credit note and a corrected invoice rather than editing it quietly. See invoice numbering for why the paper trail matters.
Because VAT registration is not enabled in your settings. Add your VAT number and rate, and subsequent quotes and invoices will show VAT as a separate line.
Issue a credit note against the incorrect invoice and raise a corrected one. Do not simply edit or delete the original — the credit note is what shows an auditor exactly what happened and why.
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