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Invoice Tax Rate Calculator

Work out the rate from a net and a gross, or the effective rate on a mixed invoice.

Fill in any two and the third is worked out from them.

Quick Tool Overview

The Invoice Tax Rate Calculator finds the rate somebody actually applied from any two of the net, tax and gross, works out the effective rate across a mixed invoice, and flags a rate that matches no real one.

What it does
Finds the tax rate that was applied
You give it
Any two of net, tax and gross
You get back
The rate, and whether it is a real one
Best for
Checking a supplier’s invoice
Invoice Tools Free, unlimited use No sign-up Runs in your browser

About the Invoice Tax Rate Calculator

Two questions come up often enough to need a tool. The first is what rate somebody actually applied: you have a net figure and a gross figure on a supplier’s invoice and you want to know whether the 17.4% it implies is a rate anywhere, or a mistake. The second is what the effective rate across a whole invoice is, when it mixes rates.

The first is division. The second is more useful than it sounds: the effective rate is what a customer sees when they divide the tax by the net, and if it is not one of the rates on the invoice — which it will not be, on a mixed invoice — somebody will ask about it. Knowing the figure before they do is worth having.

It also matches the rate against the standard rates in use around the world, so an unrecognised rate is flagged as one rather than accepted quietly. A supplier charging 19% in a 20% country is charging the German rate by accident, and that is far more common than it should be.

Key features of the Invoice Tax Rate Calculator

From any two figures

Net and gross, net and tax, or gross and tax.

Matched against real rates

A 19% charge in a 20% country is Germany by accident.

Effective rate

What a customer sees on a mixed invoice, before they ask about it.

Three decimal places

Because some real rates are fractional.

Errors named

Rate on the gross, wrong country, or compounded rounding.

How to use the Invoice Tax Rate Calculator

  1. 1

    Enter the net and the gross

    Or the net and the tax — any two of the three.

  2. 2

    Read the rate

    To three decimal places, because some real rates are fractional.

  3. 3

    Check the match

    Against the standard rates actually in use, so an odd one is flagged.

  4. 4

    For a mixed invoice, list the lines

    Each with its own rate, to get the effective rate across the whole.

Frequently asked questions

Divide the tax by the net and multiply by 100. If you only have the gross, subtract the net first: (gross − net) ÷ net × 100.

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