Important October deadlines for filing self-assessment tax returns to prevent unexpected tax bills
October is an essential month for those who are self-employed, have a side-hustle, invest, are high-earning parents paying back Child Benefit, or are landlords receiving rental income. This month marks the key tax dates that everyone in these categories should be aware of.
Firstly, October is the deadline for registering for self-assessment if you are newly self-employed or a sole trader and have earned gross income over £1,000, received any untaxed income including pension income above £2,500, or if you received income of more than £1,000 from trading or providing services online. The registration period runs from October 1st to October 5th, 2025, to comply with tax obligations for the 2024/2025 tax year.
Landlords also have to register if they received income from property, while investors may need to declare dividends or capital gains above the tax allowances. If you have already informed HMRC of your status in previous years, you don't need to register.
The deadline for filing a paper tax return is 31 October 2025, while the online deadline is 31 January 2026 for the 2024/2025 tax year. Early filing ensures accurate payments on account, reducing the risk of paying too little and incurring high interest rates from HMRC.
It's important to note that there are penalties for late registration and late payment. If a tax bill is not sent on time, an initial £100 penalty is imposed, followed by daily penalties of £10 up to a maximum of £900. If you fail to register by 5 October, you could face penalties worth up to 100% of the tax owed if HMRC suspects deliberate income concealment.
After six months, there is a further penalty of 5% of the tax due or £300, whichever is greater. The same penalty applies after 12 months. There are also penalties of 5% of the tax unpaid at 30 days, six, and 12 months.
To help determine if a self-assessment tax return is necessary, HMRC has a free online tool available. Once you've registered, the taxman will generate a unique taxpayer reference for you so you can complete a tax return.
With frozen tax thresholds, more people could be caught by the self-assessment net. Untaxed income has to be declared to HMRC through self-assessment. Filing and paying taxes early can help avoid high interest rates if an underpayment occurs.
In conclusion, October is a crucial month for those who need to file their self-assessment tax returns. By registering and filing on time, you can avoid penalties and ensure that your taxes are paid accurately and on time. You can register online at Gov.uk to make the process easier.
