Finance⏱ 4 min read

How to Calculate VAT: Add It, Remove It, and Check It

VAT trips people up constantly — especially removing it from a price that already includes it. Here's the exact method for every scenario, including the mistake almost everyone makes.

VAT (Value Added Tax) is 20% in the UK for most goods and services. The maths sounds simple — until you need to remove it from a price that already includes it, and most people get it wrong.

Adding VAT to a Net Price

This is straightforward. You have the pre-VAT price and need the final price.

Gross price = Net price × 1.20 VAT amount = Net price × 0.20 Example: £450 net price Gross (inc. VAT) = 450 × 1.20 = £540 VAT amount = 450 × 0.20 = £90

Removing VAT from a Gross Price (The Tricky One)

You have a price that already includes VAT and need the pre-VAT figure. The mistake nearly everyone makes: subtracting 20% from the gross price.

WRONG: £540 × 0.20 = £108 → £540 − £108 = £432 ✗ CORRECT: £540 ÷ 1.20 = £450 ✓

Why is subtracting 20% wrong? Because the 20% VAT was calculated on the net price, not the gross. When you subtract 20% of the gross, you're using a larger base number and get a different (wrong) result.

Net price = Gross price ÷ 1.20 VAT amount = Gross price − Net price = Gross price × (0.20 ÷ 1.20) = Gross price × 0.1667

Reduced and Zero VAT Rates

RateApplies ToDivisor to Remove
20% (standard)Most goods and services÷ 1.20
5% (reduced)Energy bills, children's car seats, some renovations÷ 1.05
0% (zero-rated)Food, children's clothing, books, newspapersNo VAT to remove
ExemptInsurance, finance, education, healthNo VAT charged at all

Zero-rated and exempt sound the same but are legally different. Zero-rated goods still count as taxable supplies for VAT registration purposes; exempt supplies do not.

Checking a VAT Receipt

On a VAT receipt, businesses must show the VAT amount separately. To verify it's correct:

Expected VAT = Net amount × 0.20 Or: Expected VAT = Gross amount × 0.1667 Example receipt: Net £83.33, VAT £16.67, Gross £100.00 Check: 83.33 × 0.20 = £16.67 ✓

VAT Registration Threshold

Businesses must register for VAT once their taxable turnover exceeds £90,000 in a rolling 12-month period (as of 2024). Below this threshold, registration is optional. Once registered, you must charge VAT on your sales but can also reclaim VAT on your business purchases.

For a small business near the threshold, the registration decision has significant cash flow and pricing implications — it's worth modelling carefully before you hit the limit rather than scrambling when you cross it.

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