Start of the UK Tax Year: 6th April
The UK tax year officially starts on 6th April each year. This marks the beginning of a new financial cycle for personal tax, and it determines how your income and allowable expenses are assessed over the next twelve months. The date may seem unusual compared to a calendar year, but it stems from historical adjustments dating back to the shift from the Julian to the Gregorian calendar.
Tax Changes That Take Effect
With the new tax year come various updates from HMRC. These may include:
- Changes to the personal allowance
- Adjustments to tax thresholds for basic, higher, and additional rates
- Updates to National Insurance thresholds
- New dividend or savings allowances
- Capital Gains Tax exemptions
Each of these changes affects how your income is taxed. Staying updated on these figures helps you forecast potential tax liabilities and structure your financial decisions accordingly. For example, the 2024/25 personal allowance remains at £12,570, which means the first portion of your income is not subject to Income Tax.
Why 6th April Matters
The 6th April is important not just because of regulatory updates. It is also the date from which any income, expenditure, profits, or losses start to count toward your tax return for that year. If you are self-employed, employed with side income, or earning from dividends or rental properties, all financial activity from this date onward is considered for your next tax return.
Getting a clear start on 6th April allows you to keep cleaner records throughout the year. Filing returns becomes easier if you begin collecting your documentation and categorising income and expenses from day one.
Adjustments to Your Tax Code
When the tax year begins, you may receive a notice from HMRC outlining your new tax code. This code instructs your employer or pension provider on how much tax to deduct from your income. It reflects allowances, deductions, and income adjustments that influence how much of your earnings are tax-free.
The most common tax code, 1257L, corresponds to the full personal allowance. However, your code may differ if you have underpaid tax in the previous year, claim work-related expenses, or receive multiple income streams. An incorrect tax code can result in overpaying or underpaying tax, so checking it for accuracy early in the tax year can prevent complications later.
Planning at the Start of the Tax Year
The beginning of the tax year is the ideal time to set up a system for managing your tax responsibilities. Starting early helps ensure that you won’t be scrambling for documents close to the submission deadline. It also allows you to track allowable expenses and stay ahead of any changes that may impact your tax liability.
Registering for Self Assessment: Deadline is 5th October
If you’ve never filed a Self Assessment tax return before, you must register with HMRC by 5th October following the end of the tax year in which you earned untaxed income. Registration is essential because it lets HMRC know that you need to file a tax return.
Who Needs to Register for Self Assessment
There are various categories of individuals who need to register for Self Assessment. These include:
- Self-employed individuals who began trading during the previous tax year
- Company directors with untaxed income or dividends
- People who earn income from property rentals
- Individuals who receive income from abroad
- Those earning significant interest or dividends
- People with income from trusts, settlements, or estates
- Individuals earning over £100,000 annually
- Employees with complicated tax situations such as multiple income streams or benefits in kind
In general, if your income is not taxed through PAYE, or if your tax affairs are complex, you are likely to need to file a return.
First-Time Self-Employed Individuals
If you have recently started working for yourself and have not previously completed a Self Assessment tax return, you are required to register with HMRC. The process is fairly straightforward but must be completed by the 5th October deadline in order to avoid penalties.
The steps are:
- Register online with HMRC
- Wait for your Unique Taxpayer Reference (UTR) to arrive by post
- Use your UTR to set up access to HMRC’s Self Assessment online services
Once set up, you’ll be able to file returns, make payments, and communicate with HMRC securely through your account. Your Income Tax and Class 2 and Class 4 National Insurance contributions will be calculated based on your submitted return.
Previously Self-Employed Individuals
If you have submitted a Self Assessment tax return in the past and become self-employed again after a break, you don’t need to re-register from scratch. Instead, you should complete a CWF1 form to update your self-employment status with HMRC.
This ensures that HMRC knows you’ve resumed self-employment and expects you to file a return. Not doing so may result in your return being flagged as late or unnecessary.
Non-Self-Employed with Additional Income
Even if you are not self-employed, you may still need to register for Self Assessment. This applies to people who receive income that has not been taxed at source.
Examples include:
- Rent from properties
- Foreign income
- Interest on savings not taxed automatically
- Share dividends
- Income from trusts
- Pension income from overseas sources
- Employment benefits not accounted for via PAYE
In these cases, you will need to complete an SA1 form and register with HMRC for Self Assessment. The deadline remains 5th October following the end of the tax year in which you earned the income.
What Happens If You Miss the Deadline
If you fail to register by the 5th October deadline, you risk being issued a penalty for failing to notify chargeability. Additionally, missing this deadline could lead to delays in receiving your UTR, which may cause problems when trying to file your return by the 31st January deadline.
To avoid these issues, it’s best to register as soon as you know you’ll need to submit a return. Even if you’re unsure, registering early allows you to remain on the safe side and gives you the option to notify HMRC later if a return is no longer necessary.
Documents Needed for Registration
Before registering, gather the following information:
- Full name and current address
- National Insurance number
- Date of birth
- Details of your business or income sources
- Start date of self-employment (if applicable)
- Email address and phone number
Having this information ready helps ensure that the process goes smoothly and reduces the risk of errors that could delay your registration.
Early Preparation for Self Assessment
Once registered, you will eventually need to file your tax return and pay any tax owed. Although the submission deadline for online returns is not until 31st January, starting early is advisable for a number of reasons.
Why Start Early
Starting early gives you time to:
- Collect all income and expense records
- Review tax code notices and pay slips
- Check for changes in allowances or deductions
- Seek professional advice if needed
- Budget for your tax bill in advance
The period between 6th April and 31st January provides more than nine months to prepare, but many taxpayers leave it until the last minute. This can result in rushed filings, errors, and limited availability of professional support.
What Records You Should Keep
Good record-keeping makes it easier to complete your tax return accurately. You should maintain:
- Sales invoices and receipts
- Bank statements
- Records of expenses
- Rental agreements and statements
- Dividend vouchers and investment statements
- Pension and employment documentation
- Evidence of charitable donations or pension contributions
- Records of capital gains or losses
Even if you use accounting software or a bookkeeper, it’s your responsibility to retain these records in case of an HMRC inquiry. Most documents must be kept for five years after the 31st January filing deadline.
Avoiding Common Mistakes
Early preparation also helps you avoid frequent mistakes such as:
- Missing income entries
- Incorrect personal details
- Failure to claim allowable expenses
- Misreporting VAT or CIS deductions
- Submitting the wrong figures due to lack of documentation
Being proactive reduces the likelihood of HMRC penalties and gives you the chance to resolve any issues before they escalate.
Payment on Account Deadline and Paper Tax Return Filing
Understanding the Self Assessment tax return deadlines is essential for every taxpayer in the UK who receives income outside the PAYE system. We focus on the second major financial milestone of the tax year: the 31st July payment on account deadline, followed by the 31st October deadline for paper tax returns. These dates carry different implications but are equally important for ensuring tax compliance and avoiding penalties.
31st July Payment on Account Deadline
For many self-employed individuals and other Self Assessment taxpayers, the end of July marks the deadline for making a second payment on account toward their annual tax liability. This installment system is designed to prevent a heavy tax burden from falling entirely at the end of the tax year.
What Is a Payment on Account?
Payments on account are advance payments made twice a year to HMRC toward your estimated Income Tax and Class 4 National Insurance contributions for the current tax year. The amounts are calculated based on your previous year’s tax bill.
The idea behind these installments is to split the total estimated tax amount into two smaller parts, making it easier for individuals to manage their tax obligations. The system is particularly relevant for those whose tax is not deducted automatically, such as sole traders, landlords, and company directors with untaxed income.
When Are the Payments Due?
There are two key dates each year:
- 31st January: First payment on account for the current tax year
- 31st July: Second payment on account for the current tax year
For instance, if your tax bill for the 2023/24 tax year was £6,000, then HMRC would expect you to make two payments on account of £3,000 each – one in January 2024 and another in July 2024. When you eventually file your tax return for 2024/25, you’ll either pay the balance or receive a refund, depending on how much you owe.
Who Needs to Make Payments on Account?
You’re required to make payments on account if:
- Your previous year’s Income Tax bill was more than £1,000
- Less than 80 percent of your tax was deducted at source (for example, through PAYE)
If you meet both conditions, HMRC will automatically expect two payments on account, unless you apply to reduce them.
Reducing Payments on Account
In certain situations, you might expect to earn significantly less in the current tax year compared to the previous one. This may be due to business slowdown, taking time off work, or changes in income sources.
HMRC allows you to apply for a reduction in payments on account. You can do this online through your Self Assessment account or by submitting form SA303.
However, caution is advised. If you reduce your payments too much and end up owing more, HMRC will charge interest on the underpaid amount. Therefore, it’s important to estimate your current year’s income as accurately as possible before requesting a reduction.
How to Make the Payment
HMRC offers multiple ways to make your payment on account:
- Online banking (Faster Payments, CHAPS or BACS)
- Direct debit (single payment or budget payment plan)
- Debit or corporate credit card online
- Through your bank or building society (with a paying-in slip)
- By cheque through the post
When making a payment, be sure to include your 11-character payment reference, which consists of your Unique Taxpayer Reference (UTR) followed by the letter K. This ensures the payment is allocated correctly.
Late Payment Consequences
Failing to make your payment on account by 31st July can lead to interest charges from HMRC. The interest is charged from the date the payment was due until it is paid in full. While HMRC usually gives some leeway in extraordinary circumstances, persistent lateness can lead to additional surcharges or formal collection action.
Interest rates for late payments are usually linked to the Bank of England base rate and are subject to change. If you are struggling to pay, it is better to contact HMRC proactively to discuss setting up a payment plan.
Benefits of Planning for 31st July
The 31st July deadline offers a chance to avoid financial stress later in the tax year. Making your second payment on account reduces the amount you’ll owe in the final balancing payment due by the next 31st January.
For those with fluctuating income, forecasting earnings and setting aside funds each month can prevent last-minute scrambling to find cash. Many sole traders and landlords prefer to calculate a monthly tax saving amount based on projected income and put it aside in a separate savings account to cover these installments.
Planning ahead allows for:
- Better cash flow management
- Fewer surprises when the balancing payment is due
- Increased accuracy when estimating future tax liability
- Peace of mind that tax obligations are being met
31st October Paper Tax Return Filing Deadline
While the majority of taxpayers now file their Self Assessment tax returns online, HMRC still permits paper submissions. However, paper tax returns have an earlier deadline of 31st October, and there are growing signs that this option may be phased out in the coming years.
Who Uses Paper Returns?
Paper tax returns are typically used by:
- Individuals who prefer non-digital methods
- Taxpayers with limited or no internet access
- Those who find paper forms easier to complete
- Individuals submitting their return via an authorised agent or accountant who uses paper
Despite these reasons, HMRC continues to encourage digital filing as the primary method. Filing online gives access to additional features like automatic calculations, confirmation of receipt, and quicker turnaround times for refunds.
Important Points About the Paper Deadline
If you choose to file a paper tax return, it must reach HMRC by 31st October following the end of the tax year. For example, for the 2023/24 tax year (which ended on 5th April 2024), your paper tax return must be received by HMRC no later than 31st October 2024.
This is a submission deadline, not a posting deadline. That means the form must arrive at HMRC by that date, not just be in the mail. You’ll need to account for postal delays, especially if sending close to the deadline.
Filing late will result in an automatic £100 penalty, even if you have no tax to pay or if you’re due a refund. Further penalties can be charged the longer the return remains outstanding.
Transition to Digital Filing
Although paper returns are still accepted, HMRC is pushing toward a fully digital system. The Making Tax Digital initiative is part of this broader move, aiming to digitise tax records and submissions for businesses and individuals.
Future tax years may bring reduced availability or eventual discontinuation of paper forms, so it’s worth considering switching to digital filing even if you’ve been using paper returns for years. Familiarity with the online system now can prevent disruption later on.
What Is Included in a Paper Return?
A full paper return can include several components, depending on your circumstances. At a minimum, the SA100 main form must be completed. Additional supplementary pages may be required, such as:
- SA103 for self-employment
- SA105 for property income
- SA108 for capital gains
- SA102 for employment income
- SA106 for foreign income
Each form contains specific fields for reporting income, expenses, deductions, and other relevant details. Accuracy is crucial, as errors or omissions may delay processing or result in penalties.
Advantages of Paper Filing
Despite the growing shift to digital methods, some taxpayers still find benefits in paper filing. These include:
- Simplicity for those uncomfortable with digital tools
- A tangible, hard copy of the submission
- The ability to review and double-check entries without digital navigation
However, these advantages are being outweighed by the speed, convenience, and efficiency of online returns. Most refunds processed through online submissions are returned more quickly than their paper counterparts.
Tips for Meeting the Paper Return Deadline
If you plan to submit your Self Assessment tax return by paper, consider the following tips to ensure you meet the 31st October deadline:
- Start filling in the form as early as possible
- Use black ink and write clearly in block letters
- Double-check all personal and financial information
- Ensure any supplementary pages are included
- Post the return using tracked or recorded delivery
- Retain a copy of the entire submission for your records
If you’re unsure about any figures or which forms to complete, consult HMRC guidance or consider seeking professional advice. Making corrections after submission can be time-consuming and may invite questions from HMRC.
Receiving a Tax Calculation
Once your paper tax return is submitted, HMRC will process it and issue a tax calculation. This will detail how much tax you owe or are due to be refunded, taking into account any payments on account already made.
If you file close to the deadline, you may receive your calculation with only a short window to arrange payment by 31st January. Early filing, whether online or by paper, is a safer approach.
31st January Deadline for Online Filing and Tax Payment
The Self Assessment deadline on 31st January is the most significant date in the UK tax calendar. It represents the final day to file your tax return online and to pay any tax owed for the previous tax year. For many taxpayers, this deadline is the culmination of months of record-keeping, preparation, and calculation. Filing late or failing to pay on time can lead to automatic penalties and interest charges, so understanding this deadline and planning accordingly is essential for financial and legal peace of mind.
Overview of the 31st January Deadline
The 31st January deadline applies to two major tax obligations:
- Submission of your Self Assessment tax return for the previous tax year
- Full payment of your tax liability for that same tax year, including any balancing payment or first payment on account for the new year
For example, for the 2023/24 tax year, which ended on 5th April 2024, the deadline to submit your tax return online and pay any tax due is 31st January 2025. Meeting this deadline ensures compliance with HMRC regulations and avoids penalties or interest that can quickly accumulate.
Online Self Assessment Filing
The majority of taxpayers now submit their Self Assessment returns using HMRC’s online portal. The digital platform offers several advantages, including instant confirmation of submission, on-the-spot calculations, and faster processing of refunds.
Who Should File a Return
You must submit a Self Assessment tax return if you:
- Are self-employed as a sole trader and earned more than £1,000
- Are a partner in a business partnership
- Are a company director receiving income not taxed at source
- Receive untaxed income from investments, savings, dividends, or property
- Have foreign income or capital gains
- Earn more than £100,000 per year
- Claim Child Benefit while earning over £50,000
- Receive income from trusts or settlements
- Have complex tax situations not handled through PAYE
If HMRC has sent you a notice to file a return, you are legally required to submit it, even if you do not think you owe any tax.
Registering for Online Filing
If you haven’t already registered for Self Assessment online services, you need to do so well in advance of the 31st January deadline. This process involves:
- Registering for Self Assessment and requesting access to HMRC’s online services
- Receiving your Unique Taxpayer Reference (UTR)
- Setting up your Government Gateway account
- Activating your online account using the activation code sent by HMRC
These steps can take up to 10 working days, especially during busy periods, so registering late in January may prevent you from filing on time.
Completing Your Tax Return
Once you’re registered and logged into the Self Assessment portal, you’ll be prompted to complete the various sections of the return. These may include:
- Employment income
- Self-employment income and expenses
- Dividend income
- Rental income
- Capital gains
- Pension income and contributions
- Bank interest
- Student loan repayments
- Gift Aid contributions
The online system automatically calculates your tax liability as you enter your figures. You’ll also be able to see if you’re due a refund or if you need to make a balancing payment.
Making Amendments
After submitting your tax return, you can still make corrections if you discover any errors. You have up to 12 months from the 31st January deadline to make amendments. For example, a return filed by 31st January 2025 can be amended until 31st January 2026.
To make changes, log in to your online account, choose the relevant tax year, and select the option to amend the return.
Paying the Tax You Owe
In addition to submitting your tax return, you must pay any outstanding tax by 31st January. This includes:
- The balancing payment for the previous tax year
- The first payment on account for the current tax year (if applicable)
What Is the Balancing Payment?
The balancing payment is the amount of tax you still owe after subtracting any payments on account made during the year. It ensures that your total tax paid matches your actual liability for the tax year.
For example, if your tax liability for 2023/24 is £5,000 and you’ve already paid £3,000 in advance through payments on account, your balancing payment of £2,000 must be paid by 31st January 2025.
First Payment on Account for the New Tax Year
Many Self Assessment taxpayers are also required to make a first payment on account for the new tax year on the same day they pay their balance payment. Each payment on account is usually half of your previous year’s tax bill.
So, if you owed £6,000 in tax for 2023/24, your payments on account for 2024/25 would be £3,000 in January and another £3,000 in July, unless you expect your income to decrease and apply to reduce your payments.
Methods of Payment
HMRC accepts several methods of payment for Self Assessment tax liabilities:
- Online or telephone banking
- Debit or corporate credit card payments
- Bank transfers (CHAPS, BACS, Faster Payments)
- Direct debit (for single or budget payment plans)
- At your bank or building society (using a paying-in slip)
- Cheque through the post
When paying, you’ll need your UTR number followed by the letter K as your payment reference. Ensure you allow time for the payment to reach HMRC before the deadline, as late payments attract interest charges from the due date.
Payment Difficulties and Time to Pay
If you’re unable to pay your tax bill by the deadline, contact HMRC as soon as possible to discuss a Time to Pay arrangement. This allows you to spread your payments over a set period.
You can usually set up a payment plan online if:
- You owe £30,000 or less
- You have no other payment plans or debts with HMRC
- Your return is up to date
- You apply within 60 days of the payment deadline
Missing the deadline without arranging a plan will lead to interest charges and possibly penalties.
Penalties for Missing the Deadline
Failing to file your Self Assessment tax return or pay the amount owed by 31st January triggers automatic penalties. These can escalate quickly if left unresolved.
Filing Penalties
- One day late: £100 fixed penalty
- Three months late: £10 daily penalties (up to 90 days)
- Six months late: Additional 5 percent of the tax due or £300 (whichever is greater)
- Twelve months late: Another 5 percent or £300 (whichever is greater)
In severe cases, additional penalties may apply if HMRC believes you have deliberately withheld information.
Payment Penalties
- 30 days late: 5 percent of unpaid tax
- Six months late: Additional 5 percent
- Twelve months late: Additional 5 percent
These penalties are in addition to daily interest charges on the amount owed. For this reason, it’s important to file even if you can’t afford to pay immediately, and then contact HMRC to arrange a payment plan.
Tips for Filing and Paying on Time
Meeting the 31st January deadline doesn’t have to be stressful if you plan ahead. Here are practical tips to help you stay organised and avoid late fees:
Start Early
Don’t wait until January to begin preparing your tax return. As early as April, begin gathering the documents you’ll need:
- Income statements
- Invoices
- Receipts for expenses
- Bank interest summaries
- Dividend vouchers
- Records of pension contributions
- Capital gains records
- Foreign income documentation
Having these ready can make the process of completing your return far more efficient.
Use the Online Calculator
When using HMRC’s digital platform, take advantage of the built-in calculator to see your estimated tax bill in real time. This can help you plan for your payment and avoid surprises.
Submit Even If You’re Unsure
If you’ve made reasonable efforts to estimate your income and are running out of time, submit your return with the best available information. You can always amend it later within the allowed window. Submitting late automatically triggers penalties, but submitting and correcting is usually a safer approach.
Maintain Accurate Records
Proper record-keeping is essential for filing an accurate return. You are required to keep your financial records for at least five years after the 31st January submission deadline. If you’re ever audited, HMRC may request documentation to verify figures on your return.
Keeping your records up to date throughout the year reduces the time spent compiling them during tax season.
Use Reminders
Set calendar reminders for the key dates:
- 31st July for second payment on account
- 5th October for registration if it’s your first time
- 31st October for paper returns
- 31st January for online return and payment
Having alerts in place helps ensure you don’t lose track of what’s due and when.
Conclusion
Understanding and meeting the Self Assessment tax return deadlines in the UK is essential for staying compliant, avoiding penalties, and maintaining control over your personal or business finances. Each stage of the tax year comes with its own responsibilities—from registering with HMRC and preparing documentation at the start of the tax year, to making advance payments in July and submitting returns by the final 31st January deadline.
Registering by 5th October ensures that HMRC recognises your need to file, especially if you are self-employed or receiving income outside the PAYE system. The beginning of the new tax year on 6th April marks an opportunity to review tax codes, adjust financial records, and take advantage of new allowances and thresholds. The 31st July deadline for the second payment on account is a crucial mid-year checkpoint, helping spread the tax burden more evenly and encouraging better cash flow planning.
For those filing by paper, the 31st October deadline requires earlier preparation and submission, while the 31st January online deadline represents the final call to report income and pay any outstanding taxes. Missing any of these deadlines can result in automatic penalties and interest charges that quickly escalate, making prompt action and preparation critical.
Ultimately, staying ahead of the tax calendar allows individuals and business owners to avoid last-minute stress, maintain accurate financial records, and make informed decisions about their tax obligations. Whether you’re filing as a sole trader, landlord, director, or investor, knowing the UK tax return deadlines empowers you to take charge of your finances throughout the year.