Tax Reminder for the Self-Employed and Landlords in the UK: Register for Self-Assessment By 5 October
- TBA
- Oct 1
- 4 min read
When living and working in the UK, most people associate October with two familiar events: the clocks going back for winter time and Halloween.
But there is something far more important than ‘trick or treat’ for many – the critical deadline for self-assessment tax registration.
Most employees in the UK pay tax automatically through the PAYE system.
However, if you have self-employed income, a side hustle, investment gains, rental income, or are part of a high-income household that must repay Child Benefit, you need to submit a self-assessment tax return to HMRC.
As income tax allowances and thresholds have been frozen in recent years, more people are falling into the self-assessment system.
Registering and filing on time is not only a legal duty but also the best way to avoid surprise tax bills and penalties.
5 October – registration deadline for first-time filers
If you became self-employed, a landlord, or earned untaxed income during the 2024/25 tax year (6 April 2024 to 5 April 2025), you must register by 5 October 2025.
Once registered, HMRC will issue you with a UTR (unique taxpayer reference), which you will use to submit your return.
You usually need to register if you are:
Self-employed/sole trader with turnover (before allowable expenses) of more than £1,000
A landlord receiving rental income – if you own UK property and collect rent, you must register and declare, though you may be able to claim relevant tax reliefs
A non-UK resident with UK taxable income (such as property rental or capital gains)
Earning more than £1,000 from a side hustle (e.g. Reselling goods or online trading)
An investor or company director receiving dividends or capital gains above the allowance
Even if you believe you owe no tax for a given year, HMRC still expects you to register if you meet the criteria.
While not every situation is legally mandatory, failing to notify HMRC when you do have a liability can result in penalties of up to 100% of the unpaid tax, particularly if HMRC believes you deliberately concealed income.
If you have registered and filed in previous years, you do not need to register again. But if your circumstances have changed, you must update your details. Missing deadlines will trigger penalties, which increase over time:
£100 late filing penalty immediately after the deadline
after 3 months: £10 per day (up to £900)
after 6 months: a further £300 or 5% of tax due (whichever is higher)
after 12 months: another £300 or 5% of tax due (whichever is higher)
If tax remains unpaid, surcharges of 5% are added after 30 days, 6 months, and 12 months, plus interest.
In other words: register and file early to save money and avoid stress.
If you miss the 5 October registration date, HMRC will usually send you a letter or email with a revised deadline (normally three months from the notice). Nonetheless, it is always safer to act sooner rather than rely on late filing arrangements.
31 October – paper tax return deadline
Once registered, you can file either online or on paper.
If you file on paper, the deadline is 23:59 on 31 October 2025. Late submission will attract penalties. Since HMRC’s online system automatically calculates tax owed, most people prefer to file online. The deadline for this is 31 January 2026, giving extra time.
31 January 2026 – deadline for payment
Regardless of whether you file on paper or online, any tax owed for the 2024/25 tax year must be paid by 31 January 2026. If you filed on paper in October, you can either pay immediately or wait until January.
We generally recommend filing and paying early, though this will depend on the cash flow of landlords and self-employed individuals. For many small business owners under financial pressure, paying later may be necessary.
Digital tax reporting coming soon
In recent years the UK has been rolling out its Making Tax Digital (MTD) scheme.
From 2026, landlords with income over £20,000 will be required to use approved software to record and submit returns.
For those with income above £50,000 in 2024/25, registration for digital tax filing becomes mandatory from 2026. The income threshold will gradually reduce in subsequent years.
This means landlords and the self-employed will not only need to complete their final return by 31 January each year but also submit quarterly updates in May, August, November and February. The aim is greater transparency and efficiency, but the process will be more frequent and rigorous.
Watch out for scams
As tax season approaches, scams are on the rise. In the past year HMRC has received more than 170,000 scam reports, including 47,000 relating to fake tax refunds.
Remember – HMRC will never request personal or bank details by text, email or phone call, and will not threaten arrest or legal action in voicemail messages. Refunds can only be claimed through HMRC’s official website. If you receive a suspicious message, always verify and report it.
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