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How to Register for VAT with HMRC: Step-by-Step Guide

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If you’re wondering how to register for VAT, the short answer is that you do it online through your Government Gateway account, and you need to act within thirty days of realising you have crossed the £90,000 threshold. Many business owners get caught out by this because it’s easy to miss the moment your turnover tips over the threshold until you’re already looking back at last month’s invoices.

The two tests that mean you need to register

There are two separate rules that can force you to register for VAT, and it helps to think of them as looking backward and looking forward.

The backward-looking test checks your turnover over any rolling twelve-month period, not your tax year. This trips people up constantly. It is not “since 6 April” or “since 1 January”. Instead, it covers any twelve consecutive months, checked at the end of every single month. So if you add up your sales from August last year to July this year and the total goes over £90,000, you must register, even if your turnover in any one calendar year looks lower.

Say a graphic designer invoiced £8,000 a month fairly consistently, then took on a big £15,000 project in June. Add up the twelve months ending in June and the total comes to £91,000. That crosses the threshold, so the backward-looking test is triggered even though nothing about “this tax year” has technically changed.

The forward-looking test is separate and, in some ways, more urgent. If you know at any point that your turnover in the next thirty days alone will exceed £90,000, you must register immediately, and your registration date is the day you realise it, not thirty days later. This usually applies to businesses that land a very large contract.

A tradesperson who signs a single £95,000 fit-out job due to be invoiced within the month needs to register straight away, not wait and see.

Our VAT Registration Threshold Calculator is worth using here, because checking a rolling twelve-month total by hand every month is tedious and easy to get wrong. It does that maths for you and flags how close you are.

What you need before you start

Government Gateway asks for a fair amount of detail in one sitting, so gathering everything first saves you from an interrupted session.

You will need:

  • Your business details, including your business type (sole trader, partnership, or limited company), trading name, and business address
  • Your Unique Taxpayer Reference (UTR), which you would already have from registering for Self Assessment or Corporation Tax
  • Your bank account details, since HMRC needs these for any VAT refunds
  • Your estimated annual turnover
  • The date you went over the threshold, or the date you expect to
  • Details of any other businesses you have owned recently, since HMRC checks for previous VAT registrations linked to you

Limited companies also need their company registration number from Companies House. If you already trade under a business bank account rather than a personal one, have those details ready too, as HMRC will not accept a personal account for a limited company’s VAT registration.

Step-by-step: registering online through Government Gateway

Here’s what the process looks like once you sit down to do it.

Step one: create or log into your Government Gateway account. If you already file Self Assessment or Corporation Tax online, you already have one. If not, you’ll need to create one first, and HMRC posts an activation code to your registered address, which can take several days. Don’t leave this until the last minute.

Step two: start the VAT registration application. From your Government Gateway dashboard, select “Register for VAT” under business taxes. The form asks whether you are registering because you have gone over the threshold, expect to go over it, or want to register voluntarily.

Step three: enter your business and turnover details. This is where you use the information you gathered earlier. You confirm your turnover figures and the date the threshold was crossed.

Step four: choose your VAT accounting scheme. Most small businesses default to standard VAT accounting, but this is also where you would opt into the Flat Rate Scheme if it suits your business. Our VAT Flat Rate Scheme Calculator can help you work out beforehand whether that scheme would actually save you money, since it is not right for every trade.

Step five: submit and wait for your VAT number. HMRC typically issues a VAT number within thirty working days, though it can take longer during busy periods. You will receive a VAT registration certificate showing your VAT number, the date your first VAT return period starts, and your effective date of registration.

A café owner who realised in March that their rolling twelve-month turnover had reached £93,000 would follow this exact process. They log the crossing date, submit their application within the thirty-day window, and receive their VAT number roughly a month later, backdated to when they crossed the threshold rather than the date HMRC processed the paperwork.

Timescales and how your effective date is worked out

The thirty-day notification deadline is not thirty days to register. It’s thirty days to notify HMRC that you need to. Miss it and you risk a late registration penalty on top of having to account for VAT you should have been charging all along.

Your effective date of registration depends on which test applied to you. Under the backward-looking test, your effective date is the first day of the second month after you crossed the threshold. So if your rolling twelve-month turnover passed £90,000 at the end of May, your effective date would be 1 July. Under the forward-looking test, your effective date is the date you realised you would exceed the threshold within thirty days, which can mean registration takes effect immediately.

A landscaping business that crossed the threshold at the end of April, using the backward-looking test, would have an effective registration date of 1 June. Every invoice you raise from 1 June onwards needs VAT added, whether or not the VAT number has physically arrived yet. This catches people out because there is often a gap between your effective date and the day HMRC actually confirms your VAT number.

What happens right after you register

Once registration goes through, a few things happen at once.

You receive your VAT number, which must appear on every invoice from your effective date forward, even during the gap before the number physically arrives (you can issue “VAT pending” invoices and reissue them once the number comes through).

Making Tax Digital rules also require you to keep digital records and file returns using MTD compatible software. This is a legal requirement, not a suggestion, and HMRC’s own portal cannot be used to file most returns manually anymore. If you don’t already use accounting software, this is the point to set it up.

Finally, HMRC also assigns you your first VAT return period. Most businesses file quarterly, and HMRC places you into one of three quarterly cycles (often called “stagger groups”) based on when you registered. Your first return is usually due one calendar month and seven days after the end of that first period, so plan your bookkeeping around that from day one.

To see what an invoice should look like once you are charging VAT, our Standard VAT Calculator shows you exactly how much VAT to add at each rate, and breaks the maths down so you can check your accounting software is calculating things correctly.

Common registration mistakes worth avoiding

Registering too late. This is the single most expensive mistake. Once HMRC identifies that you should have registered earlier, they backdate your registration and you owe VAT on everything you sold from that date, even if you never charged your customers for it. Track your rolling turnover monthly rather than waiting for a year-end shock.

Getting the effective date wrong. Some business owners assume their effective date is the date they submit the application, rather than the date the backward or forward-looking test produces. Get this wrong and you either under-declare VAT owed or overpay unnecessarily.

Leaving MTD software until after the VAT number arrives. Since digital record keeping is mandatory from your effective date, waiting until your VAT number lands to set up compatible software means you are already behind on record keeping for weeks or months.

Assuming voluntary registration works the same way. If you register voluntarily, below the threshold, HMRC still applies the same MTD and reporting rules. The paperwork isn’t lighter just because registration was your choice.

Forgetting that zero-rated sales still count towards turnover. Some business owners believe that because their sales are zero-rated for VAT, they do not count towards the £90,000 threshold. They do. Only VAT-exempt income is excluded.

Frequently asked questions

How long does it take to register for VAT with HMRC? HMRC usually issues a VAT number within thirty working days of a completed application, although this can extend during busy periods or if HMRC needs to check any details. Your effective date of registration is set independently of this processing time, based on when you crossed the threshold or expected to.

Can I register for VAT before I reach the £90,000 threshold? Yes. This is called voluntary registration and any business can apply regardless of turnover. It allows you to reclaim VAT on business purchases but also means you must charge VAT to customers and follow the same Making Tax Digital record-keeping rules as a mandatory registration.

What is the difference between the backward-looking and forward-looking VAT tests? The backward-looking test checks whether your turnover over any rolling twelve-month period has exceeded £90,000. The forward-looking test checks whether you expect to exceed £90,000 in the next thirty days alone, usually triggered by a single large contract, and requires immediate registration rather than waiting to see what happens.

Do I need a UTR to register for VAT? Yes, you need your Unique Taxpayer Reference, which you would already hold from registering for Self Assessment as a sole trader or Corporation Tax as a limited company. If you have not registered for either yet, you will need to do that first before applying for VAT.

What happens if I miss the thirty-day registration deadline? HMRC backdates your registration to the date you should have registered, meaning you owe VAT on all applicable sales from that point, whether or not you charged customers for it at the time. You may also face a late registration penalty, calculated based on how late the registration was and how much VAT was due.

Do I need special software before I can register for VAT? You do not need software to complete the registration application itself, but you are required to keep digital records and file returns through Making Tax Digital compatible software from your effective date of registration onwards. Setting this up before your VAT number arrives avoids a gap in compliant record keeping.

In summary

Registering for VAT comes down to two tests: has your turnover crossed £90,000 looking back over any twelve months, or will it cross £90,000 looking forward over the next thirty days? Either one starts a thirty-day clock to notify HMRC.

Gather your UTR, bank details, and turnover figures, apply through Government Gateway, and expect your VAT number within about a month, backdated to your correct effective date. Get digital record-keeping software in place early, and check your rolling turnover regularly so you’re never caught registering late.