What tax codes are supported?

Tax code coverage

The PAYE calculator understands these UK tax-code formats:

• Standard L-codes: 1257L, 1257L W1, 1257L M1 — apply the standard personal allowance
• BR: basic-rate flat 20% (typically second job)
• D0: higher-rate flat 40%
• D1: additional-rate flat 45%
• 0T: no allowance (every penny taxed at marginal rate)
• NT: no tax (typically expat)
• K-codes: K200 etc — adds to taxable rather than subtracting allowance, used when benefits-in-kind exceed allowance
• Scottish (S prefix): S1257L, SBR, SD0, SD1, SD2, SD3 — Scottish bands apply
• Welsh (C prefix): C1257L, CBR — currently mirrors rUK bands but tagged separately for HMRC

Setting a code

Open the employee detail page > Employment tab > Tax codes > Add code. Each code has an effective-from date. Adding a new code auto-closes the previous one (effective_to = day before).

W1/M1 non-cumulative

The W1 / M1 suffix forces the calculator to ignore year-to-date — each period stands alone. Default is cumulative (recommended).

If an employee starts mid-year without a P45, HMRC's emergency code is 1257L W1 until you get a P45 or P46 starter declaration.