Guidance

HMRC videos on understanding your tax code

Learn more about how tax codes work and reporting a change of circumstances.

Tax code letters and numbers

Watch a video about what your tax code is and how it is used by your employer or pension provider.

You will learn about:聽

  • what the numbers in your tax code mean聽
  • your tax-free amount for the year聽
  • why there are letters in tax codes聽

How tax codes work

Watch a video about how your tax code helps you pay the right amount of tax.聽

You will learn about:聽

  • your tax code and tax-free amount聽
  • how your tax-free amount is used if you are paid weekly or monthly聽
  • different rates of tax and tax rate bands聽
  • how to estimate your income tax for the year聽

Emergency tax codes

Watch a video about emergency tax codes, also known as temporary tax codes.聽

聽You will learn about:聽

  • W1, M1 and X tax codes聽
  • how emergency tax codes work聽
  • why you might have an emergency tax code聽
  • how long you will have an emergency tax code聽

Changes that can affect your tax code

Watch a video about why your tax code might change.聽

聽You will learn about:聽

  • what changes can affect your tax code聽
  • income changes and your tax code聽
  • how your tax code helps you pay the right amount of tax聽
  • tax codes and additional sources of income聽
  • tax codes and company benefits聽

Tax code changes and your pay

Watch a video to find out how tax code changes affect your pay.聽

聽You will learn about:聽

  • tax code changes when your tax-free amount increases聽
  • tax code changes when your tax-free amount reduces聽
  • tax code changes when you get a taxable company benefit聽
  • in-year adjustments聽to collect tax underpayments

Updating your details if your tax code is wrong

Watch a video about what you can do if your details are not up to date.聽

聽You will learn about:聽

  • your personal tax account
  • automatic tax code changes
  • when you can update your details
  • updating your employment or pension details
  • updating your existing income
  • adding a missing company benefit聽
  • what happens when you update your details

Starting a new job without a P45

Watch a video about what information to give your employer if you do not have a P45.

Starting a new job without a P45)

You will learn about:

  • finding your National Insurance number
  • completing and previewing the starter checklist
  • sending the starter checklist to your employer

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Updates to this page

Published 16 January 2025

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