Starting a New Job? Your Tax Checklist

Starting a new job is exciting — but get the tax admin wrong on day one and you could spend weeks on an emergency tax code, overpaying hundreds of pounds. Here is everything to check before your first payslip arrives.

Step 1: Find Your P45 Before You Start

A P45 is the document your previous employer issues when you leave. It has four parts and shows:

• Your gross pay from that employer since 6 April
• The total income tax deducted
• Your leaving date and final tax code

You hand parts 2 and 3 to your new employer's payroll department. They enter the figures into their payroll software, HMRC updates your record, and you should receive a correct cumulative tax code on your first payslip.

Keep part 1 of your P45 — you may need it for a Self Assessment return or benefits claim.

If you cannot get a P45 because your previous employer has gone into administration, or because you have lost it, tell your new employer immediately. They will give you a Starter Checklist instead (see Step 2).

Step 2: Complete the Starter Checklist Correctly

If you have no P45 (first ever job, gap in employment, returning from abroad), your new employer gives you a Starter Checklist (previously called a P46). It has three statements — you must tick the one that applies to you:

Statement	Situation	Resulting code
A	This is your first job since 6 April and you have not been receiving a taxable state benefit	1257L (cumulative) — correct for most people
B	This is your only job but you receive a state pension or have had another job since 6 April	1257L M1 (non-cumulative) — temporary
C	You have another job or receive a pension alongside this one	BR — 20% on all earnings, no personal allowance

Ticking the wrong statement is the most common cause of emergency taxation. The most common mistake is ticking C when you mean A, resulting in BR on what should be your only job. If you are unsure, ask your new employer's payroll team — not your manager.

Step 3: Verify Your First Payslip

When your first payslip arrives, check three things:

1. Tax code — should be 1257L (or 1257L M1 if you had no P45, temporarily). If you see BR, 0T, or 1257L W1/M1 after several weeks, act immediately.
2. Gross pay — confirm it matches your contracted salary (pro-rated if you started mid-month).
3. Tax deducted — use our salary calculator to verify. Enter your gross pay and tax code. If the actual deduction is significantly higher than expected, you are likely on an emergency code.

Step 4: What to Do If You Are on the Wrong Code