5 min read

How to Compute VAT in the United Kingdom

Whether you're reviewing an invoice, pricing a product, or running a business, knowing how to compute Value Added Tax (VAT) is an essential skill in the United Kingdom. Once you know the applicable VAT rate, the calculation is quick and straightforward.

This tutorial explains the basic formulas for adding VAT, removing VAT from a VAT-inclusive price, and calculating the VAT amount using simple examples.

Note: This guide explains how to calculate VAT. The VAT rate that applies depends on the type of goods or services being sold. Some items are charged at the standard rate, while others may qualify for reduced rates or be zero-rated or VAT-exempt under UK tax rules.

What You'll Learn

How to add VAT to a price
How to remove VAT from a VAT-inclusive price
How to calculate the VAT amount only
The formulas commonly used in the United Kingdom

What Is VAT?

Value Added Tax (VAT) is a consumption tax applied to many goods and services in the United Kingdom. VAT-registered businesses collect the tax from customers and account for it under UK tax regulations.

The standard VAT rate in the United Kingdom is 20%. However, some goods and services qualify for a reduced rate, are zero-rated, or are exempt from VAT. Before making any calculation, always confirm which VAT rate applies to the transaction.

How to Add VAT

Use this method when you know the original price before VAT.

Step 1: Calculate the VAT amount.

VAT Amount = Original Price × VAT Rate

For the standard UK VAT rate:

VAT Amount = Original Price × 0.20

Step 2: Add the VAT amount to the original price.

Final Price = Original Price + VAT Amount

Example

Original Price: £100
VAT Rate: 20%

Step 1

£100 × 0.20 = £20

Step 2

£100 + £20 = £120

Final Price (VAT Included): £120

If you're using a different VAT rate, simply replace 0.20 with the applicable decimal before performing the calculation.

How to Remove VAT from a VAT-Inclusive Price

If you already know the final price, including VAT, and want to find the original price before VAT was added, divide the total by 1 + the applicable VAT rate.

For the standard UK VAT rate of 20%:

Original Price = VAT-Inclusive Price ÷ 1.20

Example

VAT-Inclusive Price: £120
VAT Rate: 20%

Step 1

£120 ÷ 1.20 = £100

Step 2

VAT Amount = £120 − £100 = £20

Original Price: £100

VAT Amount: £20

If you're using a reduced VAT rate, replace 1.20 with the correct multiplier. For example, use 1.05 for 5% VAT.

How to Calculate Only the VAT Amount

If you only need to know the VAT itself, use the formula that matches the information you already have.

If You Know the Original Price

VAT Amount = Original Price × VAT Rate

Example

Original Price: £250
VAT Rate: 20%

£250 × 0.20 = £50

VAT Amount: £50

If You Know the VAT-Inclusive Price

First calculate the original price, then subtract it from the VAT-inclusive amount.

Example

VAT-Inclusive Price: £600
VAT Rate: 20%

£600 ÷ 1.20 = £500

£600 − £500 = £100

VAT Amount: £100

Quick Formula Guide

If You Know...	Formula
Original Price	VAT = Original Price × VAT Rate
Original Price	Final Price = Original Price + VAT
VAT-Inclusive Price	Original Price = VAT-Inclusive Price ÷ (1 + VAT Rate)
VAT-Inclusive Price	VAT = VAT-Inclusive Price − Original Price

Common Mistakes

Subtracting 20% directly from a VAT-inclusive price instead of dividing by 1.20.
Using 20 instead of 0.20 in the calculation.
Assuming every product or service in the UK is charged at the standard VAT rate. Some qualify for reduced rates, are zero-rated, or are VAT-exempt.
Rounding figures too early, which may cause small differences in the final amount.

Frequently Asked Questions

Is VAT always 20% in the United Kingdom?

No. While the standard VAT rate is 20%, some goods and services qualify for a reduced rate, are zero-rated, or are exempt from VAT. Always check which rate applies before making a calculation.

How do I add VAT to a price?

Multiply the original price by the applicable VAT rate to calculate the VAT amount, then add that amount to the original price.

How do I remove VAT from a VAT-inclusive price?

Divide the VAT-inclusive price by 1 + the VAT rate. For the standard UK VAT rate, divide by 1.20.

Why can't I simply subtract 20% from the final price?

Because the final price already includes both the original price and the VAT. Dividing by the VAT multiplier correctly separates the two amounts.

Why should I learn how to compute VAT?

Knowing how VAT works helps you understand invoices, prepare quotations, verify bills, compare prices, and avoid simple calculation mistakes in everyday business transactions.

Final Thoughts

Computing VAT in the United Kingdom is straightforward once you know the applicable VAT rate. If you have the original price, multiply it by the VAT rate to find the VAT amount. If you have a VAT-inclusive price, divide it by 1 + the VAT rate to determine the original price before VAT.

Before calculating VAT, always confirm whether the transaction uses the standard rate, a reduced rate, is zero-rated, or is VAT-exempt under current UK tax rules.