Invoice Company Number Validator
Check company registration numbers on invoices — UK prefixes, and the shape elsewhere.
Invoice Subtotal Calculator
Add up the lines and see the taxable base for each rate on the invoice.
Quick Tool Overview
The Invoice Subtotal Calculator adds the lines and splits the result into a taxable base per rate — which is what a mixed-rate invoice actually needs and what a tax return is filed on, rather than one figure at a blended average.
- What it does
- Works out the subtotal and the taxable bases
- You give it
- The lines, their rates and any discount
- You get back
- One base and one tax figure per rate
- Best for
- Invoices that mix tax rates
About the Invoice Subtotal Calculator
The subtotal is the figure tax is charged on, which is why it has to be right before anything else can be. On a single-rate invoice it is simply the sum of the lines after discounts. On an invoice that mixes rates it is not one figure at all — it is one taxable base per rate, and that is what the tax return is filed on.
This adds up the lines and splits the result by rate, showing the taxable base and the tax for each one separately, exactly as they have to appear on the face of a tax invoice. A basket of zero-rated books and standard-rated stationery produces two rows, not one row at a blended average — and a blended average is both wrong and impossible to reconcile.
It reads lines pasted from anywhere: a spreadsheet, an email, a quote, a supplier’s invoice. Paste and it works out what the subtotal should have been, which is also how you check somebody else’s.
Key features of the Invoice Subtotal Calculator
One base per rate
Exactly as it must appear on a tax invoice.
Discount spread properly
Every base reduced in proportion, not just one of them.
Paste from anywhere
A spreadsheet, an email or a supplier’s invoice.
Checks somebody else’s
A difference means a wrong rate, not drifting rounding.
Shipping handled
Shown separately, or as a line where it must pick up a rate.
How to use the Invoice Subtotal Calculator
-
1
Paste the lines
Description, quantity and price, separated by tabs or commas.
-
2
Add per-line rates if they differ
A fourth column with the rate, where the invoice mixes them.
-
3
Apply any whole-invoice discount
It is spread across the lines in proportion, so every base is reduced.
-
4
Read the bases
One taxable base and one tax figure per rate.
-
5
Check against the invoice
A difference means a rate is wrong somewhere, not that rounding drifted.
Frequently asked questions
The sum of the line amounts after discounts and before tax and other charges. It is the figure tax is calculated on, which is why it is shown separately.
Work out a separate taxable base for each rate and show each with its own tax amount. Averaging the rates across the invoice is wrong and cannot be reconciled to a return.
Yes, and it has to reduce every base in proportion. A flat 10% off a basket of 20% and 5% goods reduces both bases by 10%, not just one of them.
Conventionally it is shown after the subtotal as its own line, but whether it is taxed depends on your jurisdiction and on what it is delivering. Where it must be taxed at the goods rate, enter it as a line item instead.
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