L – Basic personal allowance for someone born after April 5, 1948
0T – No personal allowance
BR – All income from this source is taxed at the basic rate
DO – All income from this source is taxed at the higher rate
D1 – All income from this source is taxed at the additional rate
K – Total deductions exceed their allowances
M – Marriage Allowance receiving 10 percent of their spouse or civil partners’ personal allowance
N – Marriage Allowance providing 10 percent of their unused personal allowance to their spouse or civil partner
NT – No tax is due on this income
C – Paying income tax in Wales
S – Paying Scottish rate of Income Tax in Scotland
T – Tax office needs to review the tax code or to keep personal details confidential
W1 or M1 – Emergency tax codes for week one or month one depending on when a person gets paid.
Taxpayers can check their code on their Personal Tax Account, on the Government website GOV.UK.