The problem
Before a client approves a payroll, someone should look for changes that don't belong: a doubled overtime figure, a leaver still paid, a tax code that jumped. If a bureau runs 60 payrolls a month and a careful line-by-line comparison with last month takes 15 minutes each, that's 15 hours a month, and on a busy pay day it gets skipped.
What the AI does
Copilot in Excel can analyze a workbook, apply formulas across multiple sheets and use conditional formatting to pick out outliers. The payroll clerk exports this month's and last month's payroll summary into one workbook and asks Copilot to match employees across the two sheets, list starters, leavers and anyone whose gross pay, hours or tax code changed by more than a set amount, and highlight them. The clerk checks each flagged line against the payroll software and the client's variations before the payroll goes for approval. Copilot works within the Microsoft 365 service boundary under Microsoft's data protection addendum, and prompts aren't used to train the models.
A worked example
A three-person payroll bureau in Derby runs about 60 monthly payrolls and already pays for Microsoft 365 Business Standard. The two payroll clerks add Copilot Business and use it for the check before each payroll goes to the client.
Before
15 minutes comparing each of 60 payrolls line by line: 15 hours a month
After
About 6 minutes to export, ask Copilot and check the flagged lines: 6 hours a month
What it's worth
About $335£252€300A$484C$474 a month in time saved, against $43£32€38A$61C$60 for two Copilot Business licenses paid yearly. 9 minutes saved on each of 60 payrolls is 9 hours, at an assumed $37£28€33A$54C$53 an hour.
How to set it up
- Buy Copilot Business for the two clerks, $21.41£16.10€19.16A$30.91C$30.27 per user a month paid yearly or $25.70£19.32€22.99A$37.09C$36.32 monthly, excluding VAT, on top of the bureau's existing Microsoft 365 plan.
- Export this month's and last month's payroll summary with only the columns needed: employee reference, hours, gross pay, tax code and deductions. Leave out bank details and NI numbers.
- Put the two months on separate sheets of one workbook and ask Copilot to list starters, leavers and changes over your threshold, and highlight them.
- Check every flagged line against the payroll software and the client's variations, and note the reason for each change.
- Save the prompt that works so both clerks run the same check, and keep the payroll software as the record.
What goes wrong
- Copilot can match the wrong people if employee references are missing or duplicated, and it can miss a change. It is a second look, not a replacement for the payroll software's own reports.
- Sick pay and parental pay lines can reveal health and family details. Keep exports to the columns needed and store the workbook in the bureau's Microsoft 365, never in personal storage.
- Whether free Copilot Chat works inside Excel depends on licensing; analysis inside the workbook needs the Copilot license, charged per user.
- The totals the client approves and that go to HMRC come from the payroll software, not from Copilot's summary.