Understanding Your Tax Code: A Simple Guide

what is a tax code

Tax codes may seem like a jumble of letters and numbers, but they hold the key to how much tax you pay. Whether you’re a full-time worker, a pensioner, or someone with multiple sources of income, your tax code determines how much of your hard-earned money goes to the taxman. Let’s delve deeper into what tax codes are all about.

Table of Contents

What Is a Tax Code?

Your tax code is like a secret message between HM Revenue and Customs (HMRC) and your employer or pension provider. It tells them how much Income Tax should be deducted from your pay or pension. HMRC assigns a tax code to you based on various factors like your income, allowances, and circumstances.

When you start a new job or pension, HMRC sends your employer or pension provider your tax code. This ensures that the correct amount of tax is taken from your earnings or pension payments each pay period.

Finding Your Tax Code

Discovering your tax code is the first step towards understanding how much tax you’re paying. Here’s a closer look at where you can find your tax code:

  • Online: HMRC provides a convenient way to access your tax information through your personal tax account on their website. By signing in, you can view your current tax code for the year and even review past tax years. This online platform offers a user-friendly interface, making it easy to navigate your tax affairs from the comfort of your home.
  • HMRC App: For those on the go, the HMRC app is a handy tool to have. Available for download on mobile devices, the app allows you to check your tax code anytime, anywhere. Whether you’re commuting to work or waiting in line at the grocery store, you can stay updated on your tax situation with just a few taps on your smartphone.
  • Payslip: Your tax code is often included on your payslip, alongside other important information such as your earnings and deductions. This means you can easily keep track of your tax code each time you receive your pay. If you’re unsure where to find it, look for a section labelled “Tax Code” or “Tax Reference” on your payslip.
  • Tax Code Notice: HMRC communicates changes to your tax code through official correspondence, such as a Tax Code Notice letter. If your tax code is updated for any reason, HMRC will notify you by mail, ensuring you’re aware of any adjustments that may affect your tax obligations. Be sure to keep an eye out for these letters and review them carefully to stay informed about changes to your tax code.


By utilising these different methods, you can easily access your tax code and stay informed about your tax situation. Whether you prefer the convenience of online platforms or the traditional approach of paper documents, HMRC provides multiple avenues for you to manage your tax affairs effectively.

What Tax Code Means

Tax codes consist of a combination of numbers and letters. For instance, the most common tax code is 1257L. Let’s decode it:


  • Numbers: These digits indicate your tax-free income for the year. HMRC calculates this based on your Personal Allowance and any income you haven’t paid tax on yet.
  • Letters: They provide additional information about your tax situation.


What the Letters in Your Tax Code

The letters in your tax code convey specific information:


  • L: If your tax code ends with an ‘L’, it means you’re entitled to the standard tax-free Personal Allowance. This is the amount you can earn before you start paying Income Tax.


  • M or N: These letters indicate Marriage Allowance. If your tax code includes an ‘M’, it means you’ve received a transfer of 10% of your partner’s Personal Allowance. Conversely, an ‘N’ signifies that you’ve transferred 10% of your Personal Allowance to your partner.


  • T: A ‘T’ in your tax code means that other calculations are used to work out your Personal Allowance. This could be due to various factors like company benefits or untaxed income.


  • BR, D0, D1: These codes are used when all your income from a job or pension is taxed at the basic, higher, or additional rate, respectively. They often come into play if you have more than one source of income.


  • NT: If your tax code includes ‘NT’, it means you’re not paying any tax on that income.


  • S, C: These letters indicate that your income is taxed using the rates in Scotland (S) or Wales (C), respectively.


Special Cases

  • Emergency Tax Codes: If your tax code ends in ‘W1,’ ‘M1,’ or ‘X,’ you’re on an emergency tax code. This could happen if HMRC doesn’t receive your income details promptly due to changes in your circumstances.


  • Tax Codes with ‘K’: A tax code starting with ‘K’ means you have income not being taxed elsewhere, which exceeds your tax-free allowance. This might occur if you owe tax from a previous year or if you receive certain benefits.

Updating Your Tax Code

Ensuring your tax code accurately reflects your current circumstances is crucial to avoiding under or overpayment of taxes. Here’s why updating your tax code matters and how you can go about it:

Why Update Your Tax Code?

  1. Reflecting Changes: Life is full of changes, whether it’s starting a new job, receiving a pay rise, or retiring. Each of these changes can impact your tax situation, affecting how much tax you owe or are entitled to receive back as a refund. Updating your tax code ensures that it accurately reflects these changes, helping you avoid any surprises when it comes to tax time.

  2. Avoiding Penalties: Failing to update your tax code can result in under or overpayment of taxes. If you’re paying too little tax, you could face penalties and interest charges from HMRC. Conversely, if you’re paying too much tax, you may be missing out on money that could be better used elsewhere. Keeping your tax code up to date helps you avoid these pitfalls and ensures you’re paying the right amount of tax.

How to Update Your Tax Code

  1. Provide Relevant Information: When your circumstances change, such as starting a new job or receiving company benefits, it’s essential to provide relevant information to HMRC. Your employer or pension provider can assist you in updating your tax code by submitting details about your income and any changes to your employment status.

  2. Submit Necessary Documents: If you’ve started a new job, you’ll need to provide your employer with a P45 from your previous employment. This document contains important information about your earnings and tax contributions, helping your new employer calculate your tax code accurately.

  3. Complete a Starter Checklist: If you’re starting a new job after being self-employed or receiving benefits, your employer may ask you to complete a starter checklist. This form gathers information about your previous employment and helps your employer determine the correct tax code to apply to your earnings.

  4. Check Your Tax Code Online: You can also check your tax code online through your personal tax account on the HMRC website. If you notice any discrepancies or believe your tax code is incorrect, you can report changes to HMRC using their online service or by contacting them directly.


By taking these steps to update your tax code, you can ensure that it accurately reflects your current circumstances and avoid any unnecessary tax complications.

Why Your Tax Code Might Change

Understanding why your tax code might change is essential for staying on top of your tax obligations. Here are some common reasons why HMRC may update your tax code:

  1. Changes in Income: If your income changes, whether due to a pay rise, job loss, or a change in employment status, HMRC may adjust your tax code accordingly. This ensures that the amount of tax you pay accurately reflects your current earnings.

  2. Changes in Benefits: If you start receiving new benefits or your existing benefits change, it can affect your tax code. Certain benefits may be taxable, and HMRC may need to adjust your tax code to account for this additional income.

  3. Marital Status Changes: Getting married, entering into a civil partnership, or getting divorced can all impact your tax code. HMRC offers tax breaks for married couples and civil partners, such as the Marriage Allowance, which allows couples to transfer a portion of their Personal Allowance to their partner. Changes in your marital status may require HMRC to update your tax code to reflect these allowances accurately.

  4. Claiming Tax Relief: If you’re eligible for tax relief on certain expenses, such as work-related expenses or charitable donations, HMRC may adjust your tax code to account for these deductions. Claiming tax relief can reduce your taxable income and lower the amount of tax you owe.

  5. Annual Review: HMRC conducts an annual review of tax codes to ensure they remain accurate based on the latest information available. During this review, HMRC may update tax codes for individuals whose circumstances have changed over the past year.

Reporting Changes to HMRC

If you believe your tax code is incorrect or needs updating, you can report changes to HMRC using their online service or by contacting them directly. Here’s how:

  1. Online Service: HMRC provides an online service where you can report changes to your income, benefits, or other relevant information that may affect your tax code. By logging into your personal tax account, you can submit updates quickly and conveniently from your computer or mobile device.

  2. Contacting HMRC: If you prefer to speak with someone directly, you can contact HMRC by phone to report changes to your tax code. HMRC’s dedicated helpline can assist you with any questions or concerns you may have about your tax affairs.

By promptly reporting changes to HMRC, you can ensure that your tax code remains accurate and up to date, helping you avoid any potential issues with under or overpayment of taxes.

You Have Received A Letter From HMRC: What Do You Need To Know?


Your tax code is like a secret language that determines how much tax you pay. Understanding it can help you ensure that you’re paying the right amount and avoid any surprises come tax season. Keep an eye on your tax code, update it when necessary, and if in doubt, don’t hesitate to reach out to HMRC for assistance. After all, paying taxes doesn’t have to be taxing when you know what you’re dealing with!

Looking to wave goodbye to tax season worries? Look no further than Taxcare Accountant for top-notch accounting and tax services. Our dedicated team of professionals is here to offer expert guidance and support, ensuring you sail smoothly through the choppy waters of taxation. Whether you’re a small business owner, a freelancer, or an individual taxpayer, we provide bespoke solutions tailored to your needs. From meticulous tax planning and preparation to seamless bookkeeping and payroll services, we’ve got you covered at every turn. Don’t lose sleep over tax concerns – get in touch with Taxcare Accountant today and experience the tranquility of having a trusted partner by your side. Let’s collaborate to unlock your financial potential and minimise those tax headaches.

More To Explore
benefits of filing tax return early
Income Tax

9 Benefits of Filing Tax Returns Early

This extensive article tries to emphasise the benefits of submitting your taxes early, including how it can save you money and prevent needless worry

Why is My Self-Assessment Tax So High
Income Tax

Why is My Self-Assessment Tax So High?

Find the reasons why self-assessment tax is so high. Learn common factors influencing tax amounts and practical tips to manage your tax liabilities effectively.

Leave a Reply

Your email address will not be published. Required fields are marked *