Don’t Miss the 5 October Deadline to Register for Self-Assessment 2024/25
Chrissy Leach • 15 September 2025
Everything you need to know about registering for Self-Assessment before the 5 October 2025 deadline
If you’ve recently started earning income outside of PAYE, the clock is ticking. HMRC requires you to register for Self-Assessment by 5 October 2025 if you need to file a tax return for the 2024/25 tax year. Missing this deadline could lead to penalties, interest, and unnecessary stress.
At CJL Accountancy, we help individuals and business owners stay compliant and avoid last-minute panic. Here’s what you need to know.
Who Needs to Register for Self-Assessment?
You may need to register if you had untaxed income during the 2024/25 tax year (6 April 2024 – 5 April 2025). This can include:
- Self-employed businesses
- Partners in a business partnership
- Company directors who receive dividends or other untaxed income
- Landlords earning rental income
- Investors with taxable savings, dividends, or capital gains
- Side hustlers and content creators making money from Etsy, YouTube, TikTok, or freelancing
If HMRC doesn’t already know about your new income, you must tell them by registering for Self-Assessment.
Why Is the 5 October Deadline Important?
This deadline isn’t when you have to file or pay your tax, that comes later. Instead, it’s about telling HMRC you need to complete a tax return.
5 October 2025 – Deadline to register if you’re new to Self-Assessment for 2024/25.
31 January 2026 – Deadline to file your online return and pay any tax due.
By registering on time, you’ll avoid HMRC penalties and get your Unique Taxpayer Reference (UTR) in plenty of time, which you need to file your return.
How to Register for Self-Assessment
The process depends on your situation:
- Self-employed – Register using form CWF1.
- Not self-employed (e.g., landlords, investors, directors) – Register using form SA1.
- Partnerships – Both the partnership and individual partners must register separately.
You can register online via HMRC’s website, or we can handle the process for you.
What Happens If You Miss the Deadline?
If you fail to register by 5 October, HMRC can issue penalties for late notification. Acting early is the easiest way to stay compliant.
How CJL Accountancy Can Help
At CJL Accountancy, we specialise in helping people and small businesses stay on top of their tax obligations. We can:
- Register you for Self-Assessment
- File your return accurately and on time
- Ensure you claim all allowable expenses
- Help you plan for future tax bills so there are no surprises
Don’t Leave It Too Late
If you started earning new income in the 2024/25 tax year, remember: the deadline to register is 5 October 2025. The sooner you act, the smoother your tax return process will be.
📩 Get in touch with CJL Accountancy today, and let us take the stress out of Self-Assessment.
The key tax changes for small businesses, landlords and individuals
Learn the most common financial mistakes coaches, consultants and service-based business owners make and discover practical ways to avoid them.
Learn how business growth affects your tax, VAT, cash flow and business structure. A clear guide for UK coaches, consultants and service-based business owners.
Discover which business expenses coaches, consultants and online business owners can claim against tax. Learn how to reduce your tax bill legally and stay compliant.
Confused about tax as a coach, consultant or freelancer? Learn the basics of UK tax, Self Assessment, allowable expenses and tax planning in this simple guide.
Learn how to pay yourself from your business without stress or guesswork. A simple guide for UK coaches, consultants and service-based business owners.
Many business owners underestimate the real cost of employment beyond the salary they agree to pay
Learn how to read rental accounts and identify the key figures every UK landlord should monitor.
Learn how to read self-employment accounts and identify the key figures every UK sole trader should monitor.
Learn how to read limited company accounts, understand FRS 105 and FRS 102 Section 1A, and identify the key figures every UK company director should monitor.
