Straight answer: if you’re VAT registered and you sell a taxable good or service to another VAT-registered business, you must issue a proper VAT invoice within 30 days of the tax point. If your customer is a member of the public and doesn’t ask for one, you don’t legally have to give them anything. The bit almost nobody tells you is that raising that invoice can trigger the VAT bill before your customer has paid you a penny.
The rule in one paragraph
Under UK VAT law, once you’re VAT registered, you must issue a VAT invoice for every standard-rated, reduced-rated or zero-rated supply you make to another VAT-registered business. HMRC gives you 30 days from the “time of supply” (they call this the tax point) to get it out the door. If your customer isn’t VAT registered, the law doesn’t force you to invoice at all, though most of us do it anyway because it’s good practice and because clients expect it.
That’s the whole rule. Everything else is detail about when the clock starts and what happens if you’re late or sloppy.
What counts as the “tax point” and why it matters more than the invoice date
The tax point is the date the supply legally happens, and it’s not always obvious. There are two flavours:
- Basic tax point: the date goods are delivered or handed over, or the date a service is finished.
- Actual tax point: this overrides the basic one if you issue the invoice or receive payment before the basic tax point, or within 14 days after it. Whichever of invoice date or payment date comes first, that becomes the actual tax point.
Here’s why this matters. Say you finish a piece of consultancy work on 20 March. That’s your basic tax point. If you invoice on 2 April (13 days later, within the 14-day rule), your actual tax point stays 20 March and it falls into your March VAT quarter. If you leave it 20 days before invoicing, the basic tax point of 20 March stands anyway, so you’re still on the hook for that quarter. The only way to shift the tax point forward is to be paid or invoice earlier than completion. This is the mechanic that trips up small business owners who think “I’ll invoice next month to smooth my quarter” and then discover HMRC doesn’t care what date is on the paper if the work was already done.
The 30-day deadline, and what happens if you miss it
You have 30 days from the tax point to issue the VAT invoice. In practice, HMRC rarely fines a small business for being a few days late with a single invoice. The real risk isn’t a penalty letter, it’s your own cash flow, because most people run standard VAT accounting where you owe HMRC the VAT for the quarter the invoice falls into, not the quarter you get paid in.
I had a client, a small branding studio, who invoiced a £48,000 project on the last day of March. Big client, 60-day payment terms in the contract. The invoice sat in that client’s finance system until early June before it got paid. But because the studio was on standard VAT accounting, that £8,000 of VAT (at 20 percent on a taxable supply) was due to HMRC as part of the March quarter return, filed and paid by early May. The studio owner had to borrow against a credit line to cover VAT on money she hadn’t yet received. Nobody had explained to her that issuing the invoice, not being paid, was what created the liability.
That’s the uncomfortable truth most guides skip over: the invoice itself is a legal trigger, not just paperwork. The moment you issue it (or get paid, whichever is first), you owe that VAT to HMRC on your normal filing schedule, regardless of your customer’s payment terms. If your invoices routinely go unpaid for 30, 60 or 90 days, that gap between “VAT is due” and “cash has landed” is the single biggest cash flow trap in small business VAT, and it’s rarely mentioned next to the standard “issue within 30 days” advice.
The fix: cash accounting scheme
If you’re a small business with taxable turnover under £1.35 million a year, you can apply to use the VAT Cash Accounting Scheme. Under this scheme you only account for VAT when you receive payment, not when you invoice. It solves the exact problem above. The trade-off is you also can’t reclaim VAT on your own purchases until you’ve paid your supplier, so it’s not free money, it’s just matching the timing to reality on both sides. If you invoice with long payment terms or work with slow-paying corporate clients, this scheme is worth asking your accountant about before you get caught the way my client did.
What you must put on the invoice
A full VAT invoice needs, at minimum:
- A unique invoice number
- Your business name, address and VAT registration number
- The customer’s name and address
- The invoice date and the tax point (if different from the invoice date)
- A description of the goods or services
- The quantity and price, excluding VAT, for each item
- The VAT rate applied to each item
- The total amount excluding VAT, the VAT amount, and the total including VAT
The address requirement catches more people out than you’d think, especially anyone invoicing from a home office who’s tempted to leave it off. I’ve written a whole piece on why invoices need a proper address on them and what happens when businesses skip it, and it’s not just a VAT technicality, it’s the difference between an invoice HMRC accepts and one they can reject during a check.
Simplified invoices: when you can skip half of that
If the total value of the supply is £250 or less including VAT, and you’re a retail business or similar, you can issue a simplified VAT invoice instead. This drops the customer’s name and address and the breakdown of net and VAT amounts per item, and just needs the VAT rate and total including VAT shown clearly. This is the receipt-style invoice you get from a café or a hardware shop. Most service businesses invoicing over £250 a job won’t use this, but it’s worth knowing if you sell low-value goods.
When you don’t need to issue one at all
This is the part that surprises people who assume VAT registration means invoicing everyone for everything. You do not have to issue a VAT invoice when:
- The sale is to a member of the public who hasn’t asked for one
- The goods or services are exempt from VAT (insurance, certain financial services, some education and health services)
- You’re making a supply that’s outside the scope of UK VAT entirely, such as certain services to businesses outside the UK
- The customer is VAT registered but the supply is zero-rated and they haven’t asked (though issuing one anyway is sensible practice for your own records)
I know small e-commerce sellers who spend hours generating a full VAT invoice for every single Etsy-style consumer sale because their invoicing software defaults to it, when the law never asked them to do that in the first place. It’s not wrong to do it, it’s just not required, and if you’re doing hundreds of low-value consumer sales a month, that’s hours of admin you could hand to a bookkeeper or an automated tool instead of doing by hand out of habit.
Zero-rated and exempt sales still need records, even without a formal invoice
Just because you’re not legally required to issue an invoice for an exempt sale doesn’t mean you can skip keeping a record of it. HMRC still expects you to show what you sold, to whom, for how much, and at what VAT treatment, if they ever check your VAT return. This overlaps with what you need for your own tax filing too. I’ve covered the difference between what’s compulsory for VAT and what you need to keep for your tax return records, and the two lists aren’t identical, which confuses a lot of sole traders who assume “VAT invoice rules” and “self assessment record-keeping rules” are the same document. They’re not.
Sole traders and Self Assessment: a separate but related headache
If you’re not VAT registered at all, none of the above applies to you, but you still need to think about invoicing for your own Self Assessment return. HMRC doesn’t demand a formal invoice for every transaction if you’re below the VAT threshold, but you do need evidence of income and expenses that would survive a check. I go through exactly what counts as acceptable proof in this piece on invoices and Self Assessment, because the answer is more flexible than most accountants let on, but not as flexible as most freelancers hope.
The registration threshold and the trap of crossing it mid-year
You must register for VAT once your taxable turnover in any rolling 12-month period passes £90,000 (the threshold as of 2026). The invoicing obligation kicks in from your effective date of registration, not from when you notice you’ve crossed the line. This catches growing businesses out constantly. If you go over the threshold in June but don’t register until September because you were busy, HMRC still expects VAT accounted for on sales made from your correct registration date, and you’ll need to go back and either absorb the VAT yourself or, awkwardly, ask past customers to pay it retroactively. Watch your rolling turnover monthly, not annually, if you’re anywhere near £75,000 to £80,000.
Where AI helps here
Invoice timing errors are exactly the kind of thing that hides in plain sight across a year of paperwork, one invoice dated wrong here, a tax point miscalculated there, and nobody notices until a VAT inspection. I ran a stretch of my own invoicing history through an AI tool purely to see what it would flag, and the results were uncomfortable reading, detailed in what I found when I fed 14 months of invoices into AI, including patterns my own accountant had never mentioned. If you’re VAT registered and issuing more than a handful of invoices a month, it’s worth running the same exercise before HMRC does it for you.
The short checklist
- VAT registered, selling to a VAT-registered business: full VAT invoice, within 30 days of the tax point
- VAT registered, selling to a consumer who asks: give them a proper invoice or receipt
- VAT registered, selling to a consumer who doesn’t ask: no legal requirement, though good practice says do it anyway
- Sale under £250 including VAT: simplified invoice is fine
- Exempt or out-of-scope supply: no VAT invoice needed, but keep a record regardless
- On standard VAT accounting: the invoice date, not the payment date, decides when you owe HMRC
Frequently asked questions
Do I have to invoice a customer who isn’t VAT registered?
No, not by law. If you’re VAT registered and selling to a member of the public who hasn’t asked for an invoice, you’re not obliged to issue one, though most businesses do anyway for their own records and to look professional.
What happens if I issue a VAT invoice late?
HMRC’s official position is that a VAT invoice should go out within 30 days of the tax point. A single late invoice rarely triggers a penalty on its own, but the bigger risk is confusion about which VAT quarter the sale belongs to, and if it’s a pattern across your business, it’s the kind of thing that gets picked up during a VAT check.
Does the VAT become due when I invoice or when I get paid?
Under standard VAT accounting, it’s when you invoice (or when payment is received, whichever happens first), not when the invoice is eventually settled. This is why long payment terms can create a real cash flow gap, and it’s exactly what the Cash Accounting Scheme, available if your turnover is under £1.35 million, is designed to fix.
Can I skip the customer’s address on a simplified invoice?
Yes, for supplies of £250 or less including VAT, a simplified invoice doesn’t need the customer’s name and address, only the VAT rate and total. For full VAT invoices above that threshold, the address is required, and leaving it off is a common reason invoices get rejected or queried later.
