How to add and remove VAT, in plain English

Adding VAT means multiplying the net price by the rate; removing VAT means dividing the gross price by 1 plus the rate. Those two sentences cover almost every VAT calculation you will ever need to do. The rest of this guide explains why they work, shows the shortcut for pulling VAT out of a price you already paid, and walks through the handful of mistakes that cause most errors — so you can check any invoice, receipt or quote with confidence.

What VAT actually is

Value Added Tax (VAT) — called GST in some countries — is a consumption tax charged as a percentage of a price. The seller collects it on behalf of the government and passes it on. Because it is a percentage of the net (pre-tax) price, the arithmetic is simple in the adding direction and slightly less obvious in the removing direction. The rate varies widely: 5% in the UAE, 9% in Singapore, 10% in Australia, 19% in Germany, 20% in the UK, 23% in Ireland, and so on. Some goods and services sit at reduced rates — Irish restaurant food, for instance, has often been taxed at 13.5% rather than the 23% standard rate.

Adding VAT to a net price

If you know the price before tax, adding VAT is a single multiplication. Take the net amount and multiply by the rate expressed as a decimal, then add it back:

VAT = net × (rate ÷ 100), and gross = net + VAT.

For a £200 net invoice at 20%: the VAT is 200 × 0.20 = £40, so the gross is £240. A neat shortcut is to multiply the net by 1 + the decimal rate in one step — 200 × 1.20 = £240 — which skips the intermediate addition. At 5% you would multiply by 1.05; at 23% by 1.23.

Removing (reversing) VAT from a gross total

This is the direction that trips people up. When a price already includes VAT, the tax is inside the number, so you cannot simply subtract the rate. The correct method is to divide the gross by 1 plus the decimal rate:

net = gross ÷ (1 + rate ÷ 100), and VAT = gross − net.

For a £240 VAT-inclusive total at 20%: net = 240 ÷ 1.20 = £200, and the VAT element is £40. Notice what happens if you take the tempting shortcut of subtracting 20% of £240: you get £48, not £40, and a net of £192, which is wrong. That gap is the single most common VAT mistake, and it grows with the rate.

The VAT-fraction shortcut

There is a faster way to pull the tax out of a VAT-inclusive price: multiply by the VAT fraction. The fraction is rate ÷ (100 + rate). At 20% that is 20/120 = 1/6, so the VAT in any 20%-inclusive price is simply the price divided by six. At 5% the fraction is 5/105 = 1/21; at 23% it is 23/123, roughly 0.187. So the VAT inside a £240 bill is 240 ÷ 6 = £40, matching the division method. Memorising 1/6 for 20% and 1/21 for 5% lets you sanity-check receipts in your head.

Worked examples at three rates

UK, 20%. A freelancer quotes £500 plus VAT. The client pays 500 × 1.20 = £600. If the freelancer had instead quoted £600 including VAT, the net they keep is 600 ÷ 1.20 = £500 and the VAT to hand over is £100.

UAE, 5%. A gadget is priced at 315 AED including VAT. The net is 315 ÷ 1.05 = 300 AED and the VAT is 15 AED — exactly 1/21 of the total. Because the rate is low, the inclusive and net prices are close, which is why 5%-VAT mistakes are easy to overlook.

Ireland, 23%. A tool costs €123 including VAT. Net = 123 ÷ 1.23 = €100 and the VAT is €23. At this higher rate the difference between dividing (correct) and subtracting 23% of the gross (wrong, giving €94.71 net) is large enough to matter on every line of an invoice.

Rounding, and why lines can look a penny off

Tax authorities usually allow VAT to be calculated and rounded either per line or on the invoice total, and the two methods can differ by a penny or two. If you add up individually rounded VAT amounts they may not exactly equal the VAT on the summed total. This is normal and expected; it is not an error in the calculation. When you need an invoice to reconcile to the last cent, decide up front whether you are rounding per line or on the total and stick to it.

Net, gross and margin — keeping the words straight

Confusion often comes from vocabulary rather than maths. Net means before VAT; gross means after VAT. A price described as “plus VAT” is net, and you add tax to it. A price described as “VAT inclusive” is gross, and the tax is already inside. When a supplier quotes a figure without saying which it is, ask — a 20% VAT rate means the two differ by a sixth, which is far too much to guess.

When VAT sits alongside other charges

On some bills VAT is only one of several add-ons. Restaurants and hotels may apply a service charge and a local municipality or tourism fee as well, and the order in which they stack changes the final number. That interaction is common enough to deserve its own page: see service charge vs VAT vs tip for how a hospitality bill really adds up. To run any of the numbers above yourself, the VAT & service-charge calculator on the home page does adding, removing and full bill breakdowns instantly.