UK PAYE tool

Why Is My Pay Lower This Month?

Compare two payslips line by line. We surface what may explain the drop, ranked by impact.

What a result looks like

Sample: gross down £200, tax down £40, net down £150. Largest driver: gross pay (likely fewer hours).

Driver: gross pay

Hours / overtime / sickness pay are most likely.

Driver: tax / NI

Worth reviewing the tax code and earnings band.

Driver: deductions

Possible new pension, court order, or benefit charge.

Last: gross £2,500, tax £250, NI £130, pension £125. Net £1,995.

This: gross £2,500, tax £400, NI £130, pension £125. Net £1,845.

Tax rose £150 with no gross change - may indicate a tax code switch worth reviewing.

Why was my pay lower with no obvious change?

Common causes: tax code change, sick pay vs full pay, reduced overtime, new benefit deduction, or a bonus pushing tax higher last month.

Could a tax code change cause this?

Yes. A move from 1257L to BR or to a K code can drop net pay sharply. Worth reviewing.

Is this an HMRC official tool?

No. We are independent. We compare figures only - we do not access HMRC records.

Why does it ask for both months?

PAYE is cumulative - last month is the baseline used to flag what changed.

What if my hours changed?

Enter the actual gross. The tool will show that gross is the main driver of net change.

Last verified: 2026-05-03.

Disclaimer: Educational guidance only. Not tax or payroll advice.