# Invoice Line Item Sum Checklist

> A step-by-step checklist for invoice line items. Test the row arithmetic, subtotal, tax and amount due, and run it with Claude or ChatGPT.

## What this check is for

An invoice total is only as reliable as the rows under it. This checklist tests four things. Every line item must be complete, and the arithmetic of each line must be correct. The line totals must add up to the stated subtotal. The subtotal plus tax and other charges must give the amount due.

Accounts payable teams use the checklist before they approve a payment. Freelancers and small businesses can use it on invoices that they send or receive. The checklist finds transposed digits (digits in the wrong order), rows left out of the sum and tax on the wrong amount. It also finds a changed quantity with an old line total.

## Before you start

- Get every page of the invoice. Long invoices often show a "continued" subtotal at the bottom of each page.
- Write down the currency and if the line amounts include tax or not.
- If you want to compare prices and quantities, get the purchase order, contract or delivery note.

## The checklist

| # | Check | What to look for | Common mistakes |
|---|---|---|---|
| 1 | You find every line item | Count the rows on every page. Include credits, returns and fees under the table | The reviewer misses the last row before a page break or skips negative lines |
| 2 | Each row is complete | A description, a quantity, a unit price and a line total | A lump-sum row with no quantity, or units that are not clear (hours or days, each or per pack) |
| 3 | Line arithmetic | Quantity times unit price, minus any line discount, equals the line total | Transposed digits (54 and 45), or a price per pack multiplied by a count of units |
| 4 | Line discounts | The invoice applies each stated discount one time, as a percent or an amount | The description shows a discount, but the invoice does not subtract it |
| 5 | Lines add up to the subtotal | The sum of all line totals equals the stated subtotal | Credit lines added as positive numbers, or a page subtotal counted twice |
| 6 | Tax base and rate | The invoice charges tax only on the taxable lines, at the rate shown. The tax amount is correct | Tax on exempt items, or a rate that does not match the place of supply |
| 7 | Other charges and payments | Shipping, handling, fees, deposits and payments already made | A deposit that the customer paid but the invoice does not subtract |
| 8 | Amount due | Subtotal, minus invoice-level discounts, plus tax and other charges, minus payments, equals the amount due | A total in a different currency from the lines |
| 9 | Outside documents | Prices and quantities match the purchase order, contract or delivery note | Billed quantity higher than delivered quantity |

Allow for rounding. Some invoices calculate and round the tax on each line. In this case, the sum of the line taxes can be different by a cent or two from the tax on the subtotal. Write down the difference. Use your own policy to decide if the difference is important.

For a UK VAT invoice, HMRC lists the information that the invoice must show. For each description, it must show the quantity, the VAT rate and the amount excluding VAT. It must also show the unit price, the total excluding VAT and the total VAT ([VAT Notice 700/21, section 4.1](https://www.gov.uk/guidance/record-keeping-for-vat-notice-70021#details-to-include-on-a-vat-invoice)). For sales tax or VAT elsewhere, look up the rate at the tax authority for the place of supply.

## Record the result

Copy the rows into a spreadsheet, and let the spreadsheet calculate the sums. You can use a line sheet like this one:

| Line | Page | Description | Qty | Unit price | Discount | Stated line total | Calculated line total | Difference |
|---|---|---|---|---|---|---|---|---|
| 1 | 1 | | | | | | | |
| 2 | 1 | | | | | | | |

Then compare the totals:

| Item | Stated on invoice | Calculated | Difference |
|---|---|---|---|
| Subtotal | | | |
| Tax | | | |
| Other charges | | | |
| Amount due | | | |

Finish with one result: Pass, Pass with a rounding note, or Fail with the line numbers that do not match. Keep the sheet with the invoice, so that the next reviewer can see your results.

## Use this checklist with Claude or ChatGPT

An AI assistant can read the invoice, list the rows and do the first pass of the checks. Before you upload the invoice, remove or cover the details that the checks do not need. Examples are bank account numbers and personal addresses. Also read the data settings of your workspace. They tell how the AI service stores and uses uploaded files.

Attach the invoice (all pages) and paste this prompt:

```text
Check the attached invoice with this checklist. Answer each item separately.

1. List every line item on every page as a table: page, description,
quantity, unit price, discount, stated line total. Include credits
and negative lines.
2. Flag any row that is missing a description, quantity, unit price
or line total.
3. For each row, calculate quantity x unit price minus any line
discount, and compare it with the stated line total.
4. Add all stated line totals and compare the sum with the stated
subtotal.
5. Say which lines are taxed, the tax rate shown, and check the tax
amount.
6. List shipping, fees, deposits and payments, then check that they
and the subtotal and tax give the stated amount due.

For each item, show the numbers you used and your reasoning, then mark
it Pass, Fail or Cannot tell. At the end, list everything you could not
read or determine (blurred digits, cut-off rows, unclear units).
Do not guess missing numbers.
```

AI tools can misread digits, skip a row or make an arithmetic mistake. This happens more often with scanned or photographed invoices. Paste the extracted table into a spreadsheet and do the final sums there.

Then do a spot check (a test of a few items). Compare the number of rows with the invoice. Calculate the largest lines again by hand. Do not approve or reject a payment only on the answer of the AI.

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