Tax Code Guide

Use the code guide as a starting point

Select a code to read its meaning, then compare your situation with Inland Revenue’s declaration process. This page explains codes; it cannot establish which one is correct from a code alone.

Worked example

M and M SL are not interchangeable labels: the SL suffix indicates student-loan deductions. Likewise, a secondary-income code is chosen using your expected total income, not just the size of the second payment.

How the result is built

A tax code tells the payer how to withhold. It is not a separate final-tax calculation and it does not prove your entitlement to a credit.

Before you use the number

Tell the payer when the circumstances relevant to your code change. Tailored codes and unusual income arrangements are outside this short guide.

Official source ↗ · How we prepare and correct content · Model reviewed 26 September 2026. Examples are illustrative.