About the VAT Calculator
Adding 20% to a price and taking it back out again is the part everyone comes for, and this VAT calculator does it. But it is the least interesting thing about VAT, and it is not what makes VAT different from any other sales tax.
VAT is not a cost to a registered business. It is collected on sales, reclaimed on purchases, and only the difference is handed over. A shop that charges £20,000 of VAT and pays £8,000 of VAT remits £12,000 and is out of pocket by nothing at all. The tax lands on the final consumer, because the consumer is the only person in the chain with nobody to reclaim from.
That is the mechanic the arithmetic hides, so this calculator has modes for it: a VAT return, and a comparison of the flat rate scheme against standard accounting.
How to Use the VAT Calculator
Add VAT and Take VAT out handle a single price.
Work out a VAT return takes your net sales and net purchases for the period and gives the figure you owe — or reclaim.
Flat rate scheme vs standard compares the two ways of accounting and finds the point where they cost the same.
The rate is an input. 20% is the UK standard rate, with 5% and 0% applying to some supplies, and other countries differ.
Step-by-Step Example
A quarter with £100,000 of sales and £40,000 of purchases, at 20%.
Output VAT: 100,000 × 20% = 20,000
Input VAT: 40,000 × 20% = 8,000
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Payable: 12,000Now look at it the other way. You added £60,000 of value, and 20% of £60,000 is £12,000. The same number. That is not a coincidence — it is the reason the tax has the name it has.
The Mistake That Causes Most VAT Trouble
Treating output VAT as income.
The £20,000 you charged customers was never yours. It arrived in your bank account, it sat there looking like turnover, and it belongs to HMRC. A business that spends it has spent money it was holding on someone else's behalf, and the return falls due anyway.
This is the single most common cause of a VAT bill feeling like a shock. Nothing went wrong with the calculation — the money was counted twice, once as revenue and once as available cash.
Taking VAT Out: Divide, Do Not Subtract
If a price of £120 includes 20% VAT, the net figure is not £120 less 20%. That gives £96, and £96 plus 20% is £115.20, not £120.
The VAT was charged on the smaller number, so recovering it means dividing by 1.20 — which gives £100, and £100 plus 20% is exactly £120.
A useful shortcut: at 20%, the VAT is one sixth of the gross, not one fifth. £120 ÷ 6 = £20.
| Rate | VAT as a fraction of gross |
|---|---|
| 5% | 1/21 |
| 20% | 1/6 |
| 25% | 1/5 |
The Flat Rate Scheme Has a Hard Ceiling
Under the flat rate scheme you pay a fixed percentage of your VAT-inclusive turnover and reclaim nothing on purchases. It exists to reduce paperwork, and for some businesses it also reduces the bill.
Two things about it are worth knowing before you join.
First, the percentage applies to the gross figure. On £100,000 of net sales at 20%, a 14.5% flat rate is charged on £120,000, not on £100,000 — £17,400 rather than £14,500. That gap of £2,900 catches people out constantly.
Second, there is an exact break-even. On those figures, standard accounting costs £20,000 less whatever input VAT you reclaim. The two are equal when input VAT is £2,600, which is about £13,000 of purchases. Below that the scheme wins. Above it, it costs you.
And there is a ceiling on the whole thing:
flat rate can only save money while f < r / (1 + r)At a 20% standard rate that is 16.67%. Above it, the scheme loses even if you buy nothing at all, because turnover cancels out of both sides — so the ceiling is identical for a £50,000 business and a £5m one.
The limited cost trader rate is 16.5%. It sits one sixth of a percentage point under the ceiling, which leaves a break-even of £200 of input VAT on £100,000 of turnover — roughly £1,000 of purchases a year. It was set at very nearly the point where the scheme stops being worth anything, and if you have been put on it, that is almost certainly the finding that matters.
What Counts as Reclaimable
Not every cost carries VAT, and the return only works if you use the ones that do.
Wages and salaries carry none. Most insurance is exempt. Rent may or may not, depending on whether the landlord has opted to tax. Purchases from a supplier who is not registered carry none, whatever the invoice looks like.
Entering total costs rather than VAT-bearing costs overstates the reclaim, and it overstates it in the direction that produces an underpayment.
Registration Is a Cliff for Consumer Businesses
Crossing the registration threshold means charging VAT on everything you sell.
If your customers are businesses, they reclaim it and barely notice. If your customers are consumers, they cannot — so you either raise prices by 20% or absorb it out of your margin. At the threshold, a business selling to the public can genuinely be worse off after growing.
That is a real cliff rather than a gradual change, and it is worth modelling before turnover reaches it rather than after.
Understanding Your Result
Result is the gross or net figure in the line modes, the amount payable or reclaimable on a return, and the better of the two schemes in the comparison.
The figures gives the full breakdown.
What this means for you points out the reclaim position — that a registered business bears the net cost, not the gross.
Worth checking gives the reverse calculation, or the break-even for the flat rate scheme.
Worth knowing flags the cash-flow trap, the repayment position, or the flat rate ceiling.
When Should You Use This Calculator?
Preparing a return. Output less input, with the value-added check as confirmation.
Deciding on the flat rate scheme. The break-even is the number that decides it, not the headline percentage.
Pricing. Whether your quoted price includes VAT changes your margin by a sixth.
Checking an invoice. If the VAT is exactly 20% of the total, it has been calculated on the wrong base.
Common Mistakes
Treating output VAT as turnover. It was never income, and spending it is how VAT bills become emergencies.
Subtracting 20% to get the net price. Divide by 1.20. At 20% the VAT is a sixth of the gross, not a fifth.
Applying the flat rate to net turnover. It is charged on the gross figure, which makes it larger than it looks.
Joining the flat rate scheme on the headline percentage. Work out the break-even. On the 16.5% limited cost rate there is almost none.
Counting wages and exempt costs as reclaimable. They carry no VAT, and including them understates what you owe.
Ignoring the registration threshold until you cross it. If you sell to consumers, crossing it costs you a fifth of your margin or a fifth of your prices.
VAT rules, rates and scheme percentages vary by country and change over time. Every figure here is an estimate for planning, not tax advice — check with HMRC or an accountant before relying on it.