{"id":18884,"date":"2026-01-07T16:48:43","date_gmt":"2026-01-07T16:48:43","guid":{"rendered":"https:\/\/ctt-group.co.uk\/accountancy\/?p=18884"},"modified":"2026-01-07T16:50:26","modified_gmt":"2026-01-07T16:50:26","slug":"how-to-file-your-2024-2025-self-assessment-tax-return","status":"publish","type":"post","link":"https:\/\/ctt-group.co.uk\/accountancy\/how-to-file-your-2024-2025-self-assessment-tax-return\/","title":{"rendered":"How to file your 2024\/2025 self-assessment tax return\u00a0\u00a0"},"content":{"rendered":"
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Happy New Year! Can you believe it\u2019s now 2026??<\/h4>\n

While the rest of the world is getting to grips with this fact, those of us in Self-Assessment Tax Land are busy fumbling around in desk drawers and down the back of the sofa for receipts dated 2024.<\/p>\n

If you\u2019re in this boat, you\u2019ll know why: it\u2019s time to file your online self-assessment tax return! And if you haven\u2019t done it yet, the deadline of midnight on January 31st 2026 is fast approaching.<\/p>\n

Never fear, though, because the team at CTT Accountancy is here to help you get through it all unscathed. Here’s what you need to know…<\/p>\n

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Do I need to file a self-assessment tax return?<\/h4>\n

If you\u2019re self-employed or you\u2019ve earned extra income from a successful side project or investment in the last tax year (which ended in April 2025), you may be required to complete a self-assessment tax return.<\/p>\n

This is to ensure you\u2019ve paid the correct amount of income tax on your earrings to HMRC. It\u2019s also an opportunity to take advantage of any business reliefs you may be entitled to.<\/p>\n

Thanks to the trading allowance, you are allowed to earn up to \u00a31,000 tax-free in any given tax year, so if this applies to you, you will only need to fill in a self-assessment tax return if you want to pay voluntary class 2 National Insurance Contributions (NIC). Doing this protects your state pension entitlement and access to certain benefits.<\/p>\n

If you have received additional income from other sources in the last tax year, including rental from land or property, earnings from investments, trusts, or dividends, or have exceeded your pension allowances, you may also need to file a self-assessment return. A full list of qualifying circumstances can be found on the government website.<\/p>\n

The deadline for paper tax returns was October 31st 2025 and is now closed. It\u2019s not too late to file your online tax return though! If anything, filing an online return is good practice for the government’s new Making Tax Digital (MTD) initiative, which starts to come into effect as of April 2026.<\/p>\n

This new system will require all self-employed people and business owners to keep digital records of their income and expenses and submit these to HMRC every three months using approved software.<\/p>\n

I missed the 2024\/2025 deadline – help!<\/h4>\n

If you\u2019re reading this post midnight on January 31st 2026 and have yet to file your self-assessment tax return, you\u2019ve officially missed the deadline \u2013 but don’t panic!<\/p>\n

Although it\u2019s not an ideal situation, coming clean with HMRC and filing your tax return as soon as possible still minimises the cost and ramifications of it being late.<\/p>\n

Fines for late returns start with a fixed penalty; this is then followed by daily penalties for every day your tax return is outstanding. These cumulative charges also have interest added to them. If HMRC still hasn\u2019t received your self-assessment tax return by the end of February, you will then receive another fixed penalty \u2013 so time really is of the essence!<\/p>\n

It\u2019s worth noting that, in addition to late submissions, incorrect or inaccurate returns can also incur costs.<\/p>\n

If you\u2019re confused or concerned about completing your tax return, or unsure how to proceed with filing an overdue return, get in touch with us at CTT Accountancy for personalised support and advice<\/a> \u2013 we’re here to help!<\/p>\n

How do I register for income tax self-assessment?<\/h4>\n

If this is your fist ever self-assessment tax return, you\u2019ll need to register with HMRC to get your Unique Taxpayer Reference (UTR) before you can file an online return. If you haven’t done this yet, the deadline to register for the 2024\/2025 tax year closed on 5th October 2025, but if you contact HMRC urgently, they may still be able to help with registering you online.<\/p>\n

Once you have your 10-digit UTR (it usually arrives via post within three weeks of applying) you\u2019ll be able to sign into your Government Gateway account \u2013 your online portal for paying and managing your tax bills \u2013 and complete your submission.<\/p>\n

What paperwork do I need to file my 2024\/2025 self-assessment tax return online?<\/h4>\n

Having everything ready before you begin your tax return saves you time and stress; if you\u2019re the sort of person who files paperwork in shopping bags (you know who you are!), this might also be a good time to seek professional accountancy help!<\/p>\n

Depending on your circumstances, the following documents could be helpful:<\/p>\n