VAT-inclusive vs VAT-exclusive prices: formulas, examples and rounding

A price of 120 including 20% tax contains 100 of value before tax and 20 of tax. It does not contain 24 of tax. The percentage applies to the amount before tax, which is why reversing a tax-inclusive price requires division rather than simply subtracting the percentage.

This guide explains the arithmetic for a single percentage rate, using illustrative figures. VAT and GST rules differ across jurisdictions; the calculation does not tell you whether you must register, which rate applies, or how a cross-border supply should be treated. Use the rate and method applicable to your transaction.

If you already have those inputs, the VAT / GST calculator separates net, tax and gross and lets you export the result.

Net, tax and gross describe different amounts

For this calculation, net means the price before the percentage tax. Tax is the additional amount calculated on that net price. Gross is the total including that tax.

Term	Meaning in this calculation	Illustrative amount
Net	Price before tax	100.00
Tax	20% of the net price	20.00
Gross	Net plus tax	120.00

These definitions are specific to the pricing calculation. A payment provider might also call a receipt “net” after subtracting its fees. That is a different deduction. Label your worksheet columns clearly so a tax-exclusive sale is not confused with the amount that arrives after payment-processing costs.

How to add tax to a net amount

For a net amount N and percentage rate r:

• Tax = N × r ÷ 100
• Gross = N + tax

Suppose an illustrative project fee is 850 before tax and the applicable rate entered into your calculation is 10%. The tax component is 850 × 10 ÷ 100 = 85. The gross total is 935.

A quote should make clear whether its displayed fee includes tax. “Project fee: 850” leaves a client with a question that “850 excluding tax; tax 85; total 935” answers immediately. Include the identifiers and wording required for your actual invoice when you move from a quote to a payment request.

How to remove tax from a gross amount

For a gross amount G and percentage rate r:

• Net before rounding = G ÷ (1 + r ÷ 100)
• Included tax before rounding = G × r ÷ (100 + r)

Using a gross amount of 120 and an illustrative 20% rate gives 120 ÷ 1.20 = 100 before tax. The included tax is 120 × 20 ÷ 120 = 20.

HMRC’s explanation of adding and removing VAT illustrates this multiplication-and-division approach in its UK context. Its jurisdiction-specific rate should not be treated as the rate for a different transaction or country.

The reverse formula answers a pricing question: “How much of this total is tax at the rate I entered?” It does not establish whether that tax was correctly charged or can be reclaimed.

Why subtracting the percentage gives the wrong answer

Taking 20% off 120 produces 96. That is a 20% discount on the gross amount, not the removal of tax that was calculated on a smaller net amount.

You can check the error by rebuilding the price: 96 plus 20% is 115.20, which does not recover the original 120.

This distinction is useful beyond tax. Percentage increases and decreases are not symmetric when their starting bases differ. Always identify what the percentage is a percentage of before applying it.

Rounding can change the last decimal place

Our calculator rounds the tax component once to the selected currency’s smallest unit, then calculates the remaining amount by subtraction. This keeps net + tax = gross in both directions.

For example, a gross amount of 10.00 with an illustrative 20% included tax gives an unrounded tax component of 1.6666…. With two-decimal currency rounding, the tool shows 1.67 tax and 8.33 net.

Calculating separately for each invoice line can produce a different total from calculating once on a combined amount. Consider three lines of 0.03 before tax at an illustrative 20% rate:

Method	Calculation	Rounded tax
Each line separately	Each 0.03 line creates 0.006 tax	0.01 per line; 0.03 total
Combined net total	0.09 creates 0.018 tax	0.02 total

Neither approach should be chosen merely to obtain a preferred answer. Follow the rounding method appropriate to your invoicing requirements and use it consistently. When reconciling an invoice, reproduce the issuer’s line structure before assuming a one-cent difference is an error.

Different tax rates need separate calculations

A basket with two applicable rates cannot normally be described accurately by applying either rate to the entire total. Split the amounts by rate, calculate each group or required invoice line, then add the results.

The invoice generator accepts a tax percentage for each line and explains its rounding method. The standalone tax calculator is useful for checking one amount at one rate.

A rate of zero produces no tax arithmetically. That alone does not tell you whether a sale is zero-rated, exempt, outside a tax system or subject to another treatment. Those classifications depend on the relevant rules and facts, not on the output of a calculator.

Keep tax separate from payment fees and currency conversion

A fee deducted when a client pays is not automatically a reduction of the tax-inclusive invoice price. Similarly, changing the currency label does not perform foreign-exchange conversion or select a tax jurisdiction.

For a practical reconciliation, keep separate records of the invoice net amount, invoice tax, gross balance, any payments or credits, processing deductions and conversion amounts. Our guide to cross-border payment reconciliation explains why an invoice total and a bank receipt can differ.

For a reusable starting point, download a freelance invoice template or build a document with the invoice generator. Enter your own rate and payment instructions rather than treating an illustrative example as a live invoice.