Tax season in the UK is an essential time for individuals and businesses to handle their financial duties. Research from HMRC reveals that over 11 million taxpayers are required to file Self-Assessment tax returns annually, with a significant portion leaving submissions until the last minute. This delay often leads to penalties, unnecessary stress, and errors in tax filings. Staying organized ensures compliance with HMRC rules and avoids fines. This guide outlines all the key tax deadlines, helping you confidently manage your taxes, whether you’re an individual or a business owner.

Key Dates for Tax Season 2025/2026

Understanding the timeline for tax season 2025 is the first step to managing your taxes effectively. The tax year in the UK runs from April 6th to April 5th the following year, which is different from the calendar year. Here are the key dates you need to be aware of:

1. Start of the Tax Year: April 6, 2025

The UK tax year begins on April 6th each year, and 2025 is no different. This is the first day your income, savings, and other financial activities will be recorded for the tax year 2025/2026.

2. End of the Tax Year: April 5, 2026 

The tax year will end on April 5th, 2026. This is the final day for income, savings, and investments to be counted for your 2025/2026 tax return.

3. PAYE Key Tax Dates

For employers and employees, the PAYE (Pay As You Earn) system has specific deadlines for filing and payments. Here are the critical dates to remember for the 2025/26 tax year:

• End of the Last Tax Year and Deadline for PAYE Tax Refund
  • Deadline: 5 April 2025
  • The last day of the 2025/26 tax year and the deadline to claim any PAYE tax refund.
• First Day of the New Tax Year (2025/26)
  • Date: 6 April 2025
  • The start of the 2025/26 tax year for PAYE purposes.
• P60 Insurance Deadline
  • Deadline: 31 May 2025
  • Employers must issue P60 documents to employees by this date. P60 forms summarise employees’ total pay and tax deductions for the previous year.
• P11D Insurance Deadline
  • Deadline: 6 July 2025
  • Employers must issue P11D forms to employees. This form reports any benefits provided to employees, such as company cars or private medical insurance.
•  Payment Settlement Agreements
  • Deadline: 6 July 2025
  • Last date to agree on payment settlement agreements for the 2025/26 tax year, if applicable.
•  Deadline for Paying Class 1A National Insurance Contributions
  • Deadline: 22 July 2025
  • Employers must pay Class 1A National Insurance contributions for benefits provided to employees.
• Second Income Tax and National Insurance Payment on Account
  • Deadline: 31 July 2025
  • The second payment on account for income tax and National Insurance for the 2025/26 tax year is due by this date.

4. Self-Assessment Key Tax Dates

For individuals who file a self-assessment tax return, here are the important dates for the 2025 tax season:

• Deadline for Claiming Tax Overpaid (2025/26)
  • Deadline: 5 April 2025
  • The final day to claim any tax overpaid for the 2025/26 tax year under self-assessment.
• First Day of the New Tax Year (2025/26)
  • Date: 6 April 2025
  • The beginning of the 2025/26 tax year for self-assessment purposes.
• Deadline for Second Payment on Account for Income Tax (2025/26)
  • Deadline: 31 July 2025
  • The second payment on account for income tax for the 2025/26 tax year must be made by this date.
• Deadline to Register with HMRC if Self-Employed
  • Deadline: 5 October 2025
  • If you became self-employed or started receiving income from property during the 2023/24 tax year, you must register with HMRC by this date.
•  Deadline for Paper Self-Assessment Returns (2025/26)
  • Deadline: 31 October 2025 (midnight)
  • The last day to submit a paper self-assessment tax return for the 2025/26 tax year.
• Deadline for Online Self-Assessment Returns (2025/26)
  • Deadline: 30 December 2025
  • The last day to submit your online self-assessment tax return for the 2025/26 tax year if you owe less than £3,000 in tax.
• Deadline for Filing and Paying Self-Assessment Tax (2025/26)
  • Deadline: 31 January 2025 (midnight)
  • The final deadline for filing your online self-assessment tax return and paying any tax due for the 2025/26 tax year.
• End of Tax Year 2024/25
  • Date: 5 April 2025
  • The end of the 2025/26 tax year for self-assessment.

5. VAT Tax Return Deadlines

Small VAT-registered businesses must file quarterly VAT returns, with deadlines governed by the Making Tax Digital (MTD) for VAT legislation. Here are the typical quarterly VAT return periods and their deadlines:

Key Dates To Remember

Tax Season 2025: What You Need to Know 

Tax season can be overwhelming, especially if you’re not prepared. Here’s everything you need to know to make the process smoother and ensure you don’t miss any important deadlines.

Understanding Your Tax Obligations

1. Personal Tax Returns

“You will need to file a personal tax return if you earn income through self-employment, rental income, or other sources that aren’t taxed automatically. To do this, you must have a Tax Identification Number, as it is essential for reporting your income and completing your self-assessment. The UK government requires individuals to report their income, expenses, and any tax reliefs or allowances they wish to claim.

2. Income Tax Rates for 2025  

The UK has a progressive income tax system, meaning the more you earn, the higher the rate of tax you pay. For the tax year 2025/2026, the income tax rates are expected to remain similar to previous years, but it’s always good to double-check the latest updates from HMRC.

Here’s a quick breakdown of the income tax bands for 2025/2026 (subject to change):

3. National Insurance Contributions (NICs)

National Insurance is another important aspect of the UK tax system. If you’re employed or self-employed, you’ll need to pay NICs. The amount depends on your earnings and employment status. NICs contribute to your state pension and other benefits, so it’s vital to understand your obligations.

Preparing for Tax Season 2025

Tax season doesn’t have to be stressful. With the right preparation, you can ensure everything is in order before the deadlines hit. Here’s how you can get ready:

1. Organize Your Documents

Before you start your tax return, gather all the necessary documents. These might include:

• P60 or P87 form (if you’re employed)
• Bank statements
• Payslips
• Receipts for business expenses
• Proof of any tax reliefs or allowances you’re claiming

2. Use HMRC’s Online Tools

HMRC offers several online tools to help you manage your taxes. The self-assessment portal allows you to file your tax return online, check your tax bill, and make payments. It’s the easiest and most efficient way to handle your taxes.

3. Consider Hiring a Tax Professional

If you’re unsure about your tax obligations or need help with complicated tax matters, consider hiring a tax professional. They can provide expert advice, ensure your return is filed correctly, and help you claim all eligible deductions.

Common Tax Season Mistakes to Avoid

Tax season can be stressful, but avoiding these common mistakes can make the process smoother:

1. Missing the Deadline

The most common mistake is missing the deadline for submitting your tax return. This can result in fines and interest charges. To avoid UK tax penalties, make sure you mark the key dates on your calendar and set reminders.

2. Failing to Claim Deductions

Many taxpayers miss out on tax deductions they’re eligible for.Tax credits are another valuable way to reduce your tax bill. If you’re self-employed, for example, make sure to claim all allowable business expenses. The same goes for individuals who are entitled to tax relief on things like charitable donations.

3. Incorrect Information

Double-check the information you enter on your tax return. Incorrect details, such as wrong income amounts or missing expenses, can lead to fines or delays in processing your return.

How to Make Tax Season 2025 Less Stressful

Tax season doesn’t have to be a headache. Here are a few tips to make it easier:

• Start Early: Don’t wait until the last minute to file your tax return. Starting early will give you plenty of time to gather your documents and seek professional advice if needed.
• Stay Organized: Keep all your financial documents in one place throughout the year. This will save you time and stress when it’s time to file your tax return.

Seek Help if Needed: If you’re unsure about anything, don’t hesitate to ask for help. Whether it’s from HMRC or a professional accountant at quilliammarr, getting advice can save you from costly mistakes.

Final Thoughts!

Tax season 2025 in the UK is approaching, and preparation is key. You can navigate tax season smoothly by knowing the critical dates, understanding your obligations, and staying organized. Whether filing a self-assessment return or managing a business, staying ahead of deadlines and avoiding common mistakes will save you time, money, and stress. Need expert help? Visit Quilliam Marr for professional tax assistance. Our team is here to simplify the process and ensure you’re fully prepared for the 2025 tax season. Don’t wait—get in touch today and make tax season stress-free!