Why is Second Job Tax Higher?
No Personal Allowance
In the UK, you typically get a Personal Allowance of £12,570 tax-free each year. This is usually applied entirely to your main job (Tax Code 1257L).
For your second job, you have no allowance left. This means you pay Income Tax (usually 20%) on every single pound you earn. This calculator uses code 0T to simulate this scenario.
Tax Codes BR, D0, and 0T
- BR (Basic Rate): All income taxed at 20%. Common for second jobs.
- D0 (Higher Rate): All income taxed at 40% (if your main job already pays over £50,270).
- 0T: Zero personal allowance. Works similarly to BR for basic earners.
National Insurance Exception
Good news: National Insurance is calculated per job. You get a fresh NI allowance for your second job, meaning you won't pay NI on the second income until it exceeds the primary threshold (£242/week), provided it's a separate employer.