VAT invoices.
What a valid UK VAT invoice must show.
HMRC sets out exactly what a VAT invoice has to include. Here is that list in plain English, the three mistakes that get invoices sent back, and how DocMason builds one that passes first time.
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The required contents
Nine things HMRC expects on a full VAT invoice
A VAT invoice is the document your customer uses to reclaim the VAT you charged, so HMRC is specific about what it carries. Miss one item and it is not a VAT invoice, whatever the heading says.
- 1
A unique, sequential invoice number
One sequence, no gaps you cannot explain, never reused. INV-1001, INV-1002 and so on is fine; so is a year prefix.
- 2
The date of issue
The day you raise the invoice.
- 3
The time of supply, if it differs
The tax point: when the goods went out or the work finished. If you invoice within 14 days of that, the invoice date is the tax point and you need not print a second date.
- 4
Your name, address and VAT registration number
The business the customer is paying, exactly as registered, with the nine-digit VAT number.
- 5
The customer's name and address
Who the supply was made to. For a business customer, their trading name and address are enough.
- 6
A description of what was supplied
Enough for someone who was not there to understand it: Annual boiler service, not Services rendered.
- 7
Quantity, unit price, VAT rate and net amount for each line
Every line shows how many, how much each before VAT, which rate applies (20 percent, 5 percent or zero) and the net total for the line.
- 8
The total excluding VAT, and the total VAT
Where lines carry different rates, the VAT is shown per rate. The grand total is the sum of the two.
- 9
The rate of any cash discount offered
If you offer, say, 2.5 percent for payment within seven days, the invoice says so and the VAT is worked on the discounted amount.
The simplified invoice, for sales under 250 GBP
For a retail sale of 250 GBP or less including VAT, HMRC allows a simplified VAT invoice: your name, address and VAT number, the tax point, a description, the VAT rate per item and the total including VAT. The customer's details and the separate net and VAT figures are not required. It suits a till receipt; for anything a business customer will put through its books, issue the full invoice above.
Sent back, again
Three mistakes that get a VAT invoice bounced
Not fraud, not even carelessness. Just the three things a template made for another country, or a calculator, gets wrong for a UK business.
No VAT number on the page
The single most common reason a customer's bookkeeper sends an invoice back: without your registration number they cannot reclaim the VAT, so they will not pay until they can.
VAT worked out on the rounded total
Adding 20 percent to a rounded subtotal produces a figure that does not match the lines. HMRC's rules allow rounding per line or per invoice, but the numbers on the page have to reconcile, and a bookkeeper will check.
Prices quoted including VAT with no net shown
Telling a customer the job is 600 all in is fine; invoicing it that way is not. The invoice has to show the net, the VAT and the gross separately, or it is not a VAT invoice at all.
How DocMason builds it
Every line carries its own VAT, worked out by code
Each line on a DocMason invoice has its own VAT rate: 20 percent, 5 percent or zero. Type the job in a sentence or fill in the boxes, and the subtotal, the VAT and the total appear on the document as you go. The arithmetic is done by ordinary deterministic code in exact pence, never by the AI, so the figures on the page always reconcile.
Quoted a price that already includes VAT? Say so, or tick the option on the line, and DocMason works back to the net amount and shows the VAT separately, which is what the invoice needs to say. Your VAT number, name and address come from Business details and print on every invoice; the invoice number runs from INV-1001 upwards automatically; the issue date and the due date sit at the top of the form.
Not registered? Leave every line at zero and the VAT number blank, and the invoice prints no VAT line at all. Register later and it is one change in Settings. How to add VAT to an invoice walks through the boxes.
Instant professional templates
Send something that looks like you charge properly
An invoice that looks thrown together gets treated like one. Pick from 26 designs - these are the real ones, not pictures of them - and switch at any point, before or after you have written it. Your logo and colours go on top.
Luxury
Tradesman
Luxury Gold
Why your accountant can relax
The AI writes. It does not count.
Language models are good with words and unreliable with arithmetic, so DocMason only lets them do the first part. Every figure on a document you send is worked out by ordinary code, in exact pence, the same way every time.
It is the difference between a tool you check afterwards and one you can send without reading twice.
- VAT, discounts and totals calculated in code, never by the AI
- Money held in exact pence, so rounding cannot drift
- Every email sent on your behalf is stored in full, so you can read exactly what went out and to whom
- Your data hosted in the EU, never used to train AI models
FAQs
VAT invoice questions, answered straight
Registration, the not-registered case, the tax point and the reverse charge. Where DocMason has no switch for something, this page says so.
Something else on your mind? Ask a human.
Do I need to be VAT registered to issue a VAT invoice?
Yes. Only a VAT-registered business can issue a VAT invoice or charge VAT. Registration becomes compulsory once your taxable turnover passes HMRC's threshold over a rolling twelve months (90,000 GBP when this page was written in September 2026; check HMRC for the current figure), and you can register voluntarily below it.
What if I am not VAT registered?
Issue an ordinary invoice: the same contents minus the VAT number, with no VAT line. In DocMason, set every line to 0 percent and leave the VAT number blank in Business details; the invoice then prints no VAT line and no VAT number, which is exactly right.
Can I add VAT to an invoice later?
Not by editing one you have already sent. Raise a credit note against the original and issue a new invoice with the VAT shown. If you have just registered, HMRC lets you issue VAT-only invoices to VAT-registered customers for supplies made between your effective date of registration and the day your number arrived.
What is the time of supply?
The tax point, the date that decides which VAT period a sale belongs to. The basic tax point is when goods are delivered or a service is completed; if you invoice within 14 days of that it moves to the invoice date, and a payment received before either moves it to the payment date. Most small businesses invoice promptly and never print a separate tax point.
What about the reverse charge?
Under the domestic reverse charge for certain construction services, the invoice must state that the reverse charge applies and show the VAT the customer accounts for, without charging it. DocMason has no reverse-charge switch: set those lines to 0 percent and type the required wording, with the VAT amount, into the invoice notes.
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A VAT invoice that passes first time
3 free invoices a month. Say the job, check the VAT, download the PDF.
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