VAT Registration: When You Have No Choice

‍‌​​‌​‌​‌​‌‌​​​‌‌‌​‌‌‌‌‌‌​​​​‍SiteKiln gives you plain-English information, not legal advice. If you need advice specific to your situation, talk to a qualified accountant or VAT adviser.

The short version

Right now the UK VAT registration threshold is £90,000 of taxable turnover in any rolling 12-month period. Go over that and you must register, no matter how small you feel as a business. Below the threshold you can choose to register -- which can work well if most of your clients are VAT-registered businesses and you buy a lot of materials and kit with VAT on.

Why it matters

If you go over the threshold and don't register on time, HMRC can back-date your registration, make you pay the VAT you should have charged anyway, and add interest and penalties. That can turn a good year into a cashflow crisis. On the flip side, not registering when you mostly work for VAT-registered contractors can mean you lose money you could have reclaimed on materials, fuel and big purchases.

VAT is a tax on taxable supplies -- things you sell that aren't exempt -- and most mainstream construction work is taxable at 20%, with some jobs at 5% or 0%. The Value Added Tax Act 1994 and HMRC's guidance set out when your turnover means you're "in the club" and must register. For a small builder or trade, the key questions are: what's your rolling 12-month turnover, and who are you mainly working for (private householders or VAT-registered businesses)?

5.4.1 When you must register for VAT

You must register for VAT with HMRC if either:

• Your taxable turnover for the last 12 months is over £90,000 (current threshold).
• You expect your taxable turnover to go over £90,000 in the next 30 days alone (for example, you've landed a big contract).

"Taxable turnover" here means the total value of your VATable supplies excluding VAT, not your profit. Most standard building jobs, labour plus materials, count towards this.

HMRC's rules (and VATA 1994) say:

• You have 30 days from the end of the month when you go over the threshold to tell HMRC.
• Your effective registration date is usually the first day of the second month after you crossed it (or earlier if you agree).
• If you know you'll smash £90k in the next 30 days (for example, a signed contract), you must register based on that expectation, not wait for the invoices to actually hit.

5.4.2 When you might choose to register (even under £90k)

Plenty of small builders register for VAT voluntarily before they hit the threshold. It can make sense if:

• Most of your customers are VAT-registered contractors or developers who can reclaim the VAT you charge.
• You spend a lot on materials, plant hire, vans and tools with VAT on, and want to reclaim it.
• You want to look bigger or more "set up" to main contractors, with a VAT number on your invoices.

It's usually a bad move if:

• Most of your clients are private homeowners who can't reclaim VAT -- you either have to put your prices up or take the VAT hit yourself.
• Your turnover is small and your input VAT (VAT on purchases) is low, so there's not much to reclaim.

For some builders under £150k turnover, the Flat Rate Scheme or Cash Accounting Scheme can simplify things or help cashflow, but you want an accountant to run the numbers before you jump.

5.4.3 How the rolling 12-month test actually works

The threshold isn't "this tax year" or "last calendar year"; it's a rolling 12-month total. That means every month you look back 12 months from that point and add up all your taxable turnover.

Example from HMRC's pattern:

• On 15 July you add up the last 12 months' taxable turnover and it comes to £100,000. That's the first time it's gone over £90,000.
• You must register by 30 August.
• Your effective date of registration will be 1 September.

If you ignore it and stay unregistered, HMRC can later treat you as if you were registered from 1 September anyway, and ask you to pay the VAT you should have charged from that date.

5.4.4 Construction-specific wrinkles: who you work for

For builders and trades, VAT registration decisions often come down to client mix:

• If most of your work is for main contractors, commercial clients or developers (who are VAT-registered), being VAT-registered yourself usually makes sense -- they don't mind the VAT and you get to reclaim VAT on your costs.
• If you mostly do domestic work for homeowners, going VAT-registered can make you look 20% more expensive overnight unless you cut your net price to compensate.

On top of that, there's the Domestic Reverse Charge for construction -- for certain B2B construction services, the customer accounts for the VAT instead of you. That changes your cashflow (you charge no VAT on those invoices but are still in the VAT system and can reclaim input VAT), so builders in that space almost always need proper VAT advice.

5.4.5 What happens if you're late registering

If you should have registered but didn't:

• HMRC can register you with effect from the date you should have been registered under VATA 1994 rules.
• You may have to pay VAT on the sales you made from that date, even if you never charged it to your customers at the time.
• HMRC can add interest and penalties based on how much VAT is owed and how late you were.

Sometimes you can charge VAT to customers late or negotiate, but often it comes out of your margin. That's why keeping an eye on your 12-month total and registering on time is crucial.

Checklist -- VAT and your construction business

Use this as your "am I close?" check:

• Add up your last 12 months' taxable turnover at least once a month.
• If you're near £80-85k, start talking to an accountant about VAT and pricing.
• If you pass £90k, diary the registration deadline (30 days from month-end) and apply.
• Think about who you mainly work for -- private households or VAT-registered businesses -- before choosing voluntary registration.
• If registered, make sure your invoicing, records and software can handle VAT (and, in construction, the Domestic Reverse Charge where it applies).

Putting it together -- £88k vs £95k turnover

This is rough, just to show direction, not penny-perfect. Assume:

• You're a small builder.
• Most of your work is for VAT-registered contractors, not homeowners.
• Your materials and other costs include a fair chunk of VAT you can reclaim if you're registered.

Case 1 -- Turnover £88,000, not VAT-registered

You're under the £90k threshold, so you stay out of VAT.

• Turnover (sales to contractors): £88,000 (no VAT charged).
• Costs (materials, fuel, kit, etc., including VAT you can't reclaim): say £55,000.
• Rough profit before income tax and NIC:
  • Profit ≈ £88,000 - £55,000 = £33,000.

You've kept things simple, but you've effectively "eaten" the VAT on your costs.

Case 2 -- Turnover £95,000, VAT-registered

Now you've gone over the threshold and must register. You carry on charging similar net prices, but you now add 20% VAT to your invoices (your contractor customers can reclaim it).

• Net sales (your bit): still about £95,000.
• Plus 20% VAT you add: £19,000 collected for HMRC.
• Gross invoices to contractors: £114,000 (they reclaim the £19k, so they don't really care).

On the cost side, assume your £55,000 of costs in the first example included £9,000 of VAT (20% on £45,000 of VAT-able stuff). Now, as a VAT-registered business, you can reclaim that £9,000 as input VAT.

So commercially:

• You collect £19,000 output VAT from customers.
• You reclaim £9,000 input VAT on your costs.
• You pay HMRC the difference: £10,000 net VAT.
• Your "real" costs (excluding the VAT you've reclaimed) are now effectively £46,000 instead of £55,000.

Rough profit before income tax and NIC:

• Profit ≈ £95,000 - £46,000 - £10,000 (net VAT handed over)
• Profit ≈ £39,000.

So compared to the non-VAT £88k case

Profit jumped from roughly £33,000 to £39,000 -- about £6,000 better off, mainly because you're reclaiming VAT on your costs and your customers can reclaim what you charge them.

If most of your clients were domestic and couldn't reclaim VAT, the story changes -- you'd either have to bump your prices (risking losing work) or swallow some of the VAT yourself, which can wipe out that gain.

What to do next

• Add up your last 12 months of taxable turnover and check whether you are near the £90,000 threshold.
• If you are over, register with HMRC within 30 days of the end of the month you crossed it.
• If you are under but mostly work for VAT-registered contractors, ask your accountant whether voluntary registration makes sense.
• Make sure your invoicing software can handle VAT and the domestic reverse charge before you register.

Sources and legislation

• Value Added Tax Act 1994 -- VAT registration rules, thresholds and Schedule 1 notification requirements. legislation.gov.uk/ukpga/1994/23
• Finance Act (various) -- amendments to VAT thresholds and registration rules. legislation.gov.uk/ukpga
• Social Security Contributions and Benefits Act 1992 -- NI implications of self-employed trading income. legislation.gov.uk/ukpga/1992/4

Related guides on this site

• 5.5 VAT reverse charge for construction
• 5.13 Flat rate VAT scheme
• 5.16 VAT for builders
• 1.7 Reverse charge VAT
• 8.1 Sole trader vs limited company -- honest comparison
• 14.10 Cashflow and pricing

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