The new tax year is about to start, meaning it's the perfect time to get ahead and write down important deadlines. If you're self-employed or you run a business, this will help you plan out the forms and payments you'll need to send throughout the next twelve months. But even if you're an employee at a company, it's good to be aware of these deadlines.

Now, planning out key events in the year may not be the top of everyone's priorities. But there are some key dates that you should always put in your diary — especially if you're self-employed or an employer. Doing so will not only mean you'll have plenty of time to prepare your paperwork, but it also means you're not going to end up with any fines or penalties for missing financial deadlines.

In this guide, we'll run you through all the key events and deadlines that you should add to your calendar, including the dates for both Self Assessment and PAYE. So regardless of your employment situation, you can feel prepared as the new tax year commences.

The UK tax year runs from April 6 to April 5 the following year. So the good news is you've got time to plan out your calendar for the 2023/24 tax year, which is about to start. With that in mind, here are the upcoming key dates for both PAYE and Self Assessment that you need to know:

  • 6 April 2023: 2023/24 tax year begins
  • 31 May 2023: Deadline for P60 documents to be issued to employees by employers
  • 6 July 2023: Deadline for P11D forms to be issued to employees by employers and for reporting benefits and expenses
  • 31 July 2023: Second Payment on Account (POA) due for Income Tax for 2022/23
  • 5 October 2023: Deadline to register for Self Assessment
  • 31 October 2023: Deadline for paper Self Assessment tax returns
  • 30 December 2023: Deadline to opt into PAYE
  • 31 January 2024: Deadline for filing Self Assessment Tax Returns, balancing payment for 2022/23 tax year, and first Payment on Account for 2023/24
  • 5 April 2024: 2023/24 tax year ends

In the next few sections, we'll go into each of these key dates in more detail.

If you're self-employed or earn extra income outside of PAYE, you need to complete a Self Assessment tax return each year. This is where you declare the Income Tax you owe to HMRC. Whether you have submitted one before or you are new to Self Assessment, the dates below will help guide you in planning for the 2022-23 tax year.

6 April 2023: 2023/24 tax year begins

The new tax year starts on 6 April each year and runs to 5 April the following year. The start of the tax year is also when your Tax-Free Personal Allowance usually changes. However, this year it is the same as the previous couple of years, making the 2023/24 allowance £12,570. This means you will pay tax on any income that exceeds that threshold.

In April, you may also be given a new tax code for the year if your earnings have changed. This should be updated automatically by HMRC. If this is not the case, you may need to update your employment details yourself in your online account.

Finally, while your Self Assessment tax return for this year may not be due until the following January, this month is the perfect time to start getting your paperwork in order so you don't end up in a muddle with receipts and documents close to the deadline.

31 July 2023: Second Payment on Account due for the 2022/23 tax year

Each year, you will need to make advance payments towards your Self Assessment tax bill, known as Payments on Account. The amount of tax you are expected to pay will be based on your annual earnings from the previous year. The total is then equally split in two and paid on 31 January and 31 July.

For example, if your tax bill in 2022 was £14,000, it would be split into two payments of £7,000, due on 31 January 2023 and 31 July 2023. So, by now, you should have paid half your tax bill, and the other half will be due in July — plenty of time to plan your finances to accommodate this payment.

5 October 2023: Deadline to register for Self Assessment

This is the date on which you will need to register for Self Assessment. There are three methods of doing so depending on whether you are:

  • Self-employed and have not submitted for Self Assessment before: if you're new to Self Assessment, you'll need to register through your business tax account using your Government Gateway user ID and password. Once your registration is complete, you'll receive a letter from HMRC containing your Unique Taxpayer Reference Number which you will need in order to set up your online account for Self Assessment.
  • Self-employed and have previously submitted for Self Assessment: you'll need to re-register for Self Assessment and Class 2 National Insurance online using form CWF1, using your existing ID and password.
  • Not self-employed: if you earn income outside of PAYE, such as from other employment or renting property, you need to register for Self Assessment using form SA1.

31 October 2023: Deadline for paper Self Assessment tax returns

The deadline for paper Self Assessment tax returns is three months earlier than for online tax returns, which is useful if you end up needing more time to fill yours out. It's also worth being aware that if you're one of the many people who still use paper tax returns, they are being phased out in the coming years. Now is an excellent time to get to grips with the online system — the earlier, the better, after all!

30 December 2023: Deadline to opt into PAYE

If you earn income that can be taxed under PAYE and your tax bill is under £3000, you can opt for the tax owed to be automatically collected under your tax code. In order to do this, you need to file your tax return by 30 December 2022.

31 January 2024: Deadline for online Self Assessment tax returns for the 2022/23 tax year and balancing payment for the 2022/23 tax year

By midnight on 31 January, you must have submitted your Self Assessment tax return for the 2022/23 tax year. This is also the deadline for paying any outstanding tax owed from the previous year. It is crucial that you ensure payments are received by this date, as you may incur interest charges and possible penalties if your tax bill is not cleared by the deadline.

Remember that HMRC helplines and tax advisors will be incredibly busy close to the deadline and may not be available to answer queries in the time available. For this reason, it's recommended that you give yourself plenty of time to complete your tax return. It's also worth being aware that you can complete the form in stages and save it as you go. Doing this will help ensure that your tax return is not delayed past the deadline if you get stuck and need advice.

31 January 2024: First Payment on Account due for the 2023/24 tax year

The first Payment on Account for the 2023/24 tax year is due on 31 January 2024. This is when you are required to pay half of your tax bill for the previous tax year. The second Payment on Account will be due the following July.

5 April 2024: 2023/24 tax year ends

This date marks the end of the 2023/24 tax year. After this date, you may be issued a new tax code or find that the Personal Allowance changes. So keep an eye on the government website to find out whether this is the case.

If you are an employer, it is your responsibility to maintain Pay as You Earn (PAYE), which is the system used for making National Insurance (NI) and Income Tax contributions to HM Revenue and Customs (HMRC) before salary payments are made to your employees. You must also ensure that you submit the appropriate forms throughout the tax year, along with deducting Income Tax, National Insurance and any other student loan repayments or pension contributions from your employees' salaries.

So, to help you plan out your year to ensure these responsibilities are taken care of, here are the key UK tax dates that you need to know for this year.

6 April 2023: 2023/24 tax year begins

As an employer, you are required to prepare a payroll record and assign the appropriate tax code for each employee at the start of the tax year. You must also update your payroll software so that it runs using the current Income Tax, National Insurance, and student loan repayment thresholds and rates.

31 May 2023: Deadline for P60 documents to be issued to employees

By 31 May 2023, you must issue a P60 form to each employee. This summarises their pay and any deductions made throughout the year.

6 July 2023: Deadline for P11D forms to be issued to employees and reporting benefits and expenses

As an employer, you may offer your employees benefits in kind. These are additional job perks that are offered on top of standard salaries, such as gym memberships, company cars, and healthcare insurance. Employers are required to pay Class 1A National Insurance contributions on benefits and expenses. These are declared using a P11D form which you need to submit by 6 July 2023 — the deadline for online National Insurance contributions is 22 July 2023.

As benefits in kind essentially increase a salary, employees will pay Income Tax on them. Therefore, you need to make your employees aware of this and notify them of any changes to their tax code. Additionally, you will need to provide employees with a copy of their P11D form.

5 April 2024: 2023/24 tax year ends

At the end of the tax year, employers must send a final payroll report called a Full Payment Submission (FPS) to the tax office. This declares payments to employees and the deductions made from their salaries. You are required to include all paid employees within the company and submit your FPS on or before your employees' last payday of the tax year.

Below are the answers to FAQs to help guide you in preparing to fill out your paperwork for the upcoming tax year.

What if I make a mistake on my tax return?

If you make a mistake on your tax return after you've filed it, you can amend it within 12 months of the Self Assessment deadline — this is the 31 January 2024 for the 2022/23 tax year. This can be done online or by posting another paper tax return to HMRC.

If you need to update an online tax return, you'll need to wait 72 hours from the submission time before you can make amendments to it. Once this time has passed, here's how to correct mistakes on your online tax return:

  1. Use your Government Gateway ID and password to sign into your Government Gateway account.
  2. Click 'Your tax account' followed by 'Self Assessment account'.
  3. Click on the left-hand menu and then 'At a glance', followed by 'Tax return options'.
  4. Find the tax year you want to make amendments to.
  5. Go into the tax return and update it.
  6. File the tax return again.

Alternatively, if you need to update a paper tax return, you'll need to download a new paper tax return form and post it to HMRC. When filling out the new form, write 'amendment' on each page, along with your Unique Taxpayer Reference (UTR) and your name. If you're unsure of your UTR, you can find it on letters sent from HMRC.

Remember, you must make amendments before the tax return deadline. If you miss the deadline, you must write to HMRC.

What do I do if my tax code is wrong?

Usually, your tax code will be automatically updated by HMRC if your income changes. But if HMRC has the wrong information about how much you are earning, it's possible that you will be given an incorrect tax code. If this is the case, you can use the check your Income Tax online service to update your employment details or contact HMRC to notify them about changes in your income that may have impacted your tax code. Alternatively, can contact HMRC directly to report a change in income.

Once you have notified HMRC about a change in earnings, you'll be contacted if your tax code is changed. HMRC will also inform your employer or pension provider to state that your tax code has been amended. If you are employed, your next payslip will show your new tax code and any adjustments to your pay if you were paying the wrong amount of tax.

Finally, in some cases, you may be put on an emergency tax code if HMRC does not have updated details of your employment. For example, if you change jobs or you become employed after being self-employed. If this happens, you'll be given one of the following temporary emergency tax codes:

  • 1257 W1
  • 1257 M1
  • 1257 X

If you are put on an emergency tax code, you'll pay tax on income above the Personal Allowance — currently, this is earnings over £12,570. This is a temporary measure, and once HMRC has received confirmation about your employment details from your employer, they will update your tax code. However, if your change in employment situation means you have not paid the right amount of tax, you will stay on the emergency tax code until you have paid enough tax for the year.

What happens if I pay too much tax?

If you're employed, or you get a pension, and you pay too much tax by the end of the tax year, HMRC'll notify you, and you'll receive a tax calculation letter — also known as a P800. This letter will tell you how to reclaim overpaid tax.

If you are notified that you can claim the tax online, you will need to use your Government Gateway ID and password. If you don't already have these, you'll need to create a Government Gateway account. Additionally, to complete the process, you'll need your National Insurance Number and one of the following:

  • Your valid UK passport
  • A P60 form for the last tax year
  • A payslip from the past three months
  • A DVLA-issued driving licence
  • Information on your credit file, such as credit cards or loans

Once you have this information to hand, you can sign into your account and claim overpaid tax online.

Alternatively, if you're self-employed and you've paid too much tax from Self Assessment, log into your online HMRC account and click 'request a payment'. Or, use the online service and request a refund — this service is available for all taxpayers.

What are the Income Tax rates for the 2023/24 tax year?

The amount of Income Tax you pay each tax year depends on two factors:

  • How much of your annual income exceeds your Personal Allowance
  • How much of your annual income falls within each Income Tax band

Below are the different tax bands and the taxable income thresholds for the 2023/24 tax year. The table also shows the current Personal Allowance for the new tax year.

BandTaxable IncomeTax rate
Personal AllowanceUp to £12,5700%
Basic Rate£12,571 to £37,70020%
Higher Rate£37,201 to £125,14040%
Additional Rateover £125,24145%

So, if your annual income for the upcoming tax year is £35,000, you will pay tax on the remaining amount that exceeds the £12,570 threshold at a rate of 20%. This means you'll pay £4,486 in Income Tax.