VAT for small businesses: when to register and what changes

VAT is one of those things that small business owners know they'll eventually need to deal with — and then suddenly it's urgent. Your turnover creeps past the threshold, HMRC sends a letter, and you're scrambling to understand something you should have planned for six months earlier.

This guide walks you through the basics: when you must register, what changes when you do, and the options that can make VAT simpler to manage.

When you must register

You must register for VAT when your taxable turnover exceeds £90,000 in any rolling 12-month period. This isn't based on the tax year or your financial year — HMRC looks at any consecutive 12-month window.

"Taxable turnover" means the total value of everything you sell that isn't VAT-exempt. It includes zero-rated sales (like most food or children's clothing) even though those carry 0% VAT. It does not include exempt sales (like financial services or most healthcare).

You must also register if you expect your taxable turnover to exceed £90,000 in the next 30 days alone — for example, if you land a single large contract.

Once registered, the deregistration threshold is £88,000. If your turnover drops below this, you can apply to deregister.

Voluntary registration

You can register for VAT before reaching the £90,000 threshold. This makes sense if most of your customers are VAT-registered businesses, because they can reclaim the VAT you charge — so it doesn't cost them anything. Meanwhile, you can reclaim VAT on your own business purchases.

Voluntary registration is common for B2B service businesses, consultants, and contractors. It's less useful if you sell mainly to consumers, who can't reclaim VAT and will simply see your prices increase by 20%.

What changes when you register

Once VAT-registered, four things change:

You charge VAT on your sales. Most goods and services carry the standard 20% rate. You must show VAT separately on your invoices. If you currently charge £1,000 for a service, you'll now invoice £1,000 + £200 VAT = £1,200. If your customers are VAT-registered, this shouldn't affect demand — they reclaim the £200. If they're consumers, your prices effectively increase by 20% unless you absorb the VAT.

You reclaim VAT on your purchases. Every business expense that includes VAT becomes cheaper. A £600 laptop that previously cost you £600 now costs £500 (you reclaim the £100 VAT). Software subscriptions, office supplies, professional services, equipment — the VAT on all of these comes back to you. For businesses with significant costs, this reclaim can offset a large proportion of the VAT you charge.

You file VAT returns. Quarterly by default (though annual accounting is available for smaller businesses). Each return calculates: VAT you charged on sales (output VAT) minus VAT you paid on purchases (input VAT). If output > input, you pay HMRC the difference. If input > output (common in the early stages of a business or after a large capital purchase), HMRC refunds you.

You keep digital records. Since April 2022, all VAT-registered businesses must use Making Tax Digital (MTD) compatible software to keep digital VAT records and submit returns. Spreadsheets alone are no longer sufficient — you need software that can file digitally to HMRC via their API.

The flat rate scheme

If your VAT-taxable turnover is below £150,000, you may be able to use the Flat Rate Scheme (FRS). Instead of tracking VAT on every individual purchase and sale, you pay HMRC a fixed percentage of your gross turnover. The percentage varies by business type:

In the first year of registration, you get an additional 1% discount.

The appeal of FRS is simplicity: you don't need to track input VAT on every receipt. The trade-off is that you can't reclaim VAT on most purchases (with the exception of capital goods over £2,000 including VAT).

The "limited cost trader" rule applies if your goods costs (not services) are less than 2% of turnover or less than £1,000 per year. If you're a limited cost trader — which includes most service businesses that buy very few physical goods — you must use a flat rate of 16.5% regardless of your business category. This significantly reduces the benefit of FRS for many service businesses.

Making Tax Digital

All VAT-registered businesses must comply with Making Tax Digital (MTD). This means:

• Keeping digital records of all sales and purchases
• Using MTD-compatible software (not just a spreadsheet) to maintain those records
• Submitting VAT returns digitally through the software
• Maintaining "digital links" between your records and your returns — meaning no manual re-keying of data

Popular MTD-compatible software for small businesses includes Xero, QuickBooks, FreeAgent, and Sage. Most cloud accounting packages have been MTD-compatible for several years. If you're already using one, you're likely already compliant.

From April 2026, Making Tax Digital for Income Tax (MTD ITSA) also begins for sole traders and landlords with income over £50,000. This is separate from VAT MTD but uses the same principle of digital record-keeping and quarterly reporting.

Common VAT mistakes

Not monitoring your rolling 12-month turnover. HMRC calculates the threshold on any rolling 12-month period, not your financial year. If your busiest months are clustered together, you could breach the threshold without realising. Check monthly.

Forgetting to charge VAT from the registration date. You must charge VAT from the "effective date of registration" — which might be backdated if you should have registered earlier. VAT you should have charged but didn't is still owed to HMRC, and it comes out of your pocket.

Claiming input VAT on non-business expenses. You can only reclaim VAT on purchases that are wholly for business use. Mixed-use items (like a phone used for personal and business calls) need to be apportioned. HMRC does check.

Missing the filing deadline. VAT returns are due one calendar month and seven days after the end of each quarter. Late filing triggers a penalty under HMRC's points-based system — accumulate enough points and you get a financial penalty.

Not keeping proper records. VAT invoices must include specific information: your VAT number, the date, the customer's details, a description of goods or services, the net amount, the VAT rate, and the VAT amount. Missing any of these means the invoice isn't a valid VAT invoice, which can cause problems for your customers' input VAT claims.