VAT explained: adding it vs removing it

VAT looks simple until you have a gross, tax-inclusive price and need to find the net figure hidden inside it. The instinct to just subtract the rate is where most mistakes happen.

Adding VAT

Adding VAT is straightforward: take the net price, multiply by the rate, and add it on. At 20%, a £100 net price becomes £120 gross — £100 plus £20 of tax. Multiply the net by 1.20 and you get there in one step.

Removing VAT is not subtraction

Here is the trap. If a gross price is £120 including 20% VAT, the VAT is not 20% of £120. The 20% was added to the smaller net figure, not the total. Subtracting 20% of £120 (£24) leaves £96 — which is wrong.

To reverse it correctly you divide by 1.20, giving £100 net and £20 VAT. The bigger the rate, the bigger the error from subtracting instead of dividing.

Why it matters

Anyone invoicing, pricing products or reclaiming VAT has to move between net and gross constantly. Getting the direction wrong understates your tax and overstates your margin — small percentages that add up fast across many transactions.

Let the tool handle it

Rather than remember which way to divide, use the calculator below: switch between adding and removing VAT, pick any rate, and it always shows the net, the VAT and the gross together.

Adding VAT and removing it are different sums

Adding VAT is intuitive: multiply the net figure by 1.20 for the standard 20% rate. Removing it is where the errors live. The gross figure is 120% of the net, so to get back you divide by 1.20 — you do not subtract 20%. On a £120 gross price, dividing gives £100 net and £20 VAT. Subtracting 20% gives £96, which is wrong by £4 and wrong in the same direction every time.

A useful shortcut for the standard rate: the VAT inside a gross figure is the gross divided by six. £120 ÷ 6 = £20. For the reduced 5% rate, the VAT inside a gross figure is the gross divided by 21. These only work for those specific rates, but those are the two you will meet most.

The rates and what falls under them

The UK operates three rates. The standard rate of 20% covers most goods and services. A reduced rate of 5% applies to a defined list including domestic fuel and power, children's car seats and some energy-saving materials. A zero rate of 0% applies to most food, books, newspapers, children's clothing and public transport.

Zero-rated and exempt sound identical and are not. A zero-rated business charges VAT at 0% and can still reclaim the VAT it pays on its own purchases. An exempt business charges no VAT and cannot reclaim its input VAT, which makes exemption a genuine cost rather than a relief. Financial services, insurance, postage and most education and healthcare are exempt rather than zero-rated, and the distinction shapes the economics of those sectors considerably.

Registration and the threshold

Registration becomes compulsory once taxable turnover crosses the threshold in any rolling twelve-month period — not a tax year or a calendar year, but any twelve consecutive months, which is a trap for a business with a strong seasonal peak. You must also register if you expect to cross it in the next thirty days alone.

Voluntary registration below the threshold is sometimes worth it. If your customers are VAT-registered businesses they reclaim whatever you charge, so registration costs them nothing and lets you reclaim your own input VAT. If your customers are consumers, registration effectively raises your prices by a fifth or cuts your margin by the same, and is usually best delayed.

Why prices look different B2B and B2C

Consumer-facing prices must be displayed inclusive of VAT — the price on the shelf is the price at the till. Business-to-business prices are conventionally quoted excluding it, because the buyer will reclaim it and the net figure is the one that affects them. This is why a trade quote can look dramatically cheaper than a retail price for the same item when the two are in fact identical.

When comparing quotes, the single most important check is whether each one includes VAT. A quote at £1,000 plus VAT and one at £1,150 including VAT differ by £50 in favour of the second, but they look like the opposite at a glance.

Common mistakes

Three recur. Subtracting 20% instead of dividing by 1.2, as above. Applying VAT to a zero-rated item because the invoice template defaults to the standard rate. And rounding at the wrong point — VAT should be calculated on the total of a line or invoice as specified in the rules, not rounded per unit and then summed, which can drift by pennies on high-volume invoices and eventually fails a reconciliation.