VAT inclusive pricing: how to work out the tax

A VAT inclusive price already contains the tax, so the customer pays exactly the number on the label. To find the tax inside it, multiply the price by the rate and divide by 100 plus the rate. At 20 percent that is one sixth of the price, not 20 percent of it. A 12.00 item contains 2.00 of VAT, and the shop keeps 10.00.

That one calculation is where most of the confusion starts. The rest of this post covers the two ways of pricing, the mistake and its size, and what tax inclusive pricing does to your margin, your discounts, your refunds and your next rate change. None of it is tax advice: the rules differ by country, so check the details with your accountant.

Inclusive and exclusive prices

There are two ways to put a price on a shelf.

• Inclusive: the label is the final price. Tax is inside it. This is normal in the UK, the EU, Australia, Sri Lanka, India and most of the world.
• Exclusive: the label is the price before tax, and tax is added at the till. This is how the United States and Canada work, where sales tax varies by state, province and sometimes city.

Same item, same tax, different number on the label. At 20 percent, an item that is 12.00 inclusive is 10.00 exclusive.

Why consumer shops usually show inclusive prices

In many places it is not a choice. In the UK, the Price Marking Order defines the selling price of goods sold to consumers as the final price, including VAT and all other taxes. EU law, through the Price Indication Directive, defines the selling price in the same terms. A shop selling only to trade customers can show prices before VAT; a shop selling to the public cannot.

Even where the law is looser, inclusive prices are kinder to the customer and to you. Nobody reaches the till to find the total is more than they expected, and the cashier never has to explain a number that was not on the shelf. Check your local rules, but if your customers are the public and your country has VAT or GST, assume inclusive.

How to calculate VAT from an inclusive price

The formula:

tax = gross x rate / (100 + rate)

and then:

net = gross - tax, or equivalently net = gross / (1 + rate as a decimal)

At 20 percent: 12.00 x 20 / 120 = 2.00. Net is 12.00 / 1.20 = 10.00. Since 20 / 120 is exactly one sixth, at 20 percent you can simply divide the price by six.

At 18 percent: 59.00 x 18 / 118 = 9.00. Net is 59.00 / 1.18 = 50.00. Here the fraction is 18 / 118, roughly 15.25 percent of the price.

The common mistake, and its size

The mistake is taking the rate straight off the shelf price: 20 percent of 12.00 is 2.40, so the tax “must be” 2.40 and the net 9.60.

It is not. 2.40 is 20 percent of the gross, but VAT is 20 percent of the net. Going the other way works: 10.00 plus 20 percent is 12.00. Going backwards by the same percentage does not, because the base is different.

The size of the error is tidy: it overstates the tax by exactly the tax rate. At 20 percent, 2.40 is 20 percent more than the true 2.00. At 18 percent, 18 percent of 59.00 is 10.62 against a true 9.00, again 18 percent too much. Across a year of takings, that is a meaningful gap between what you think you owe and what you do.

Calculate margin on the net price

The VAT in your till is not yours. You collect it and pass it on, so any margin worked out on the shelf price is flattering you by the tax.

Take an item that costs you 6.00 and sells for 12.00 at 20 percent VAT. On the shelf price it looks like a 50 percent margin: 6.00 profit on 12.00. On the net price of 10.00, the profit is 4.00 and the margin is 40 percent. Ten points of margin vanished because a sixth of the price belonged to the tax authority all along.

So when you work out a price, start from cost and target margin to get the net price, then add VAT on top to get the shelf price. There is more on that method in how to set a shelf price that pays, and on why margin and markup give different answers in markup vs margin.

Rounding: per line or per receipt

Tax rarely comes out in whole pennies, so it has to be rounded, and where you round changes the answer slightly.

Three items at 1.10 each, at 20 percent. Per line, each contains 1.10 / 6 = 0.1833, which rounds to 0.18, so the receipt shows 0.54 of VAT. Per receipt, the total of 3.30 contains 3.30 / 6 = 0.55. Same sale, a penny apart.

Neither is wrong in itself, but pick one method and use it consistently, and never round the tax down every time to keep the difference. Rules on rounding vary by country, and some tax authorities set out what they accept, so this is one to ask your accountant about.

Whichever you use, the receipt should show the total the customer paid and, beneath it, the tax included in that total. The customer can see what they paid in tax, and the figure is what your daily records will add up. A Z report normally shows the day’s tax collected, and it is worth glancing at when you cash up the till so a strange figure is caught the same day.

Discounts and returns

When a price comes down, the tax inside it comes down in proportion. It is always the same fraction of whatever the customer actually pays.

Take the 12.00 item at 20 percent with 25 percent off. The customer pays 9.00. The tax inside is 9.00 / 6 = 1.50, not the 2.00 the full price carried, and the net is 7.50.

Returns follow the sale, not the shelf. If that item comes back, you refund the 9.00 the customer paid, and the tax you reverse is the 1.50 that was in it. Reversing 2.00 would claim back tax you never collected. The same logic applies to a discount on the whole basket: each line carries its share of it, and the tax on each line shrinks to match.

When the rate changes

A VAT rate change hits an inclusive shop differently from an exclusive one. In an exclusive shop the till simply adds the new rate. In an inclusive shop the shelf price stays put unless you change it, so you have two options: eat the change, or reprice.

Sri Lanka’s rise from 15 to 18 percent at the start of 2024 is a good example. An item priced at 57.50 at 15 percent had a net of 50.00. At 18 percent, the same 57.50 contains 8.77 of tax and leaves a net of 48.73. Hold the price and you lose 1.27 on every one sold. To keep the net at 50.00, the shelf price has to go to 59.00.

There is no right answer for every line. Known-value items might be worth holding for a while; most other lines should move. The mistake is not deciding at all and letting the tax rise come out of your margin by default.

Where StoreWave sits

Each shop in StoreWave chooses whether its prices include tax or have tax added at checkout. In inclusive mode the customer pays exactly the shelf price, the tax is worked out from the whole sale rather than line by line, and the receipt shows it as “includes” beneath the total rather than as an extra charge. Discounts reduce the price before the tax is taken out, and a return credits its proportional share of the tax the original sale carried.

Every sale, held sale and return records which mode it was rung in. If you switch the setting later, a return or a reprint of an older sale still uses the rules it was sold under, so your history does not change when your pricing does.