Answers · UK 2025/26

How is my first payslip worked out if I start a job mid-month?

Your first pay is pro-rated for the days actually worked, usually by calendar days or working days in that period. On a GBP 30,000 salary starting on the 16th of a 30-day month, you are paid for 15 days: GBP 30,000 / 12 = GBP 2,500 monthly, x 15/30 = GBP 1,250 gross before tax and National Insurance.

Last updated: 10 June 2026Last reviewed: 10 June 2026How we verify

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When you join part way through a pay period, employers pro-rate that first payslip so you are paid only for the days you worked. Two common methods exist: calendar-day apportionment (days worked divided by days in the month) or working-day apportionment (working days divided by working days in the month) - your contract or payroll policy sets which. Example using calendar days: GBP 30,000 salary, starting on the 16th of a 30-day month means 15 days paid. Monthly gross is GBP 30,000 / 12 = GBP 2,500; pro-rated = GBP 2,500 x 15/30 = GBP 1,250. Tax and National Insurance then apply to that GBP 1,250. On a cumulative 1257L code your first-month tax-free allowance is GBP 1,047.50, so taxable pay is GBP 202.50 x 20% = GBP 40.50 Income Tax; NI is charged on pay above the GBP 1,047.50 monthly threshold (GBP 12,570 / 12), so GBP 202.50 x 8% = GBP 16.20. If you start with no P45 you may be put on an emergency or Week 1/Month 1 code, which can over- or under-tax this part-month until HMRC issues the correct cumulative code; any difference is corrected later through payroll or a P800. Holiday entitlement for the part-year is pro-rated separately. Use the Take-Home Pay calculator to estimate your steady full-month net pay, and check tax-code rules at gov.uk/tax-codes.