Who must register
Self Assessment is the system HMRC uses to collect Income Tax that is not taken automatically through PAYE. If you have income that has not already been taxed at source, the responsibility is on you to report it. You generally need to register and file a return if any of the following apply:
- You are self-employed as a sole trader and your gross trading income is above the trading allowance.
- You are a partner in a business partnership.
- You receive rental income from property above the relevant allowance.
- You are a company director with income to report that is not fully taxed under PAYE.
- You have significant savings, investment or dividend income that needs reporting.
- You have capital gains to declare.
- You or your partner receive Child Benefit and your income is above the threshold at which the High Income Child Benefit Charge applies.
- You have foreign income that is taxable in the UK.
There are other situations too, so if you are unsure, it is worth checking rather than assuming. HMRC provides a checker, and we are happy to confirm whether you need to file. The point to hold on to is that the obligation sits with you, HMRC will not always prompt you.
The key deadlines
Self Assessment runs on a set of fixed dates tied to the tax year, which runs from 6 April to the following 5 April. Three dates matter most.
5 October, register
If you need to file for the first time, you must tell HMRC by 5 October following the end of the tax year in which you had the income. For example, if you started trading in the tax year ending 5 April, you register by the following 5 October. Registering gives you the Unique Taxpayer Reference you need to file.
31 October, paper returns
If you file a paper tax return, the deadline is 31 October after the end of the tax year. Few people file on paper now, but if you do, this earlier date applies.
31 January, online filing and payment
For online returns, both the filing and the payment of any tax owed are due by 31 January following the end of the tax year. This is the deadline most people work to, and it is also when the first payment on account can fall due (see below).
How to register
Registering is done through HMRC. The exact route depends on your situation, registering as self-employed is slightly different from registering because of untaxed property or investment income, but the principle is the same: you tell HMRC you need to file, and they set you up in the system.
Once registered, you will receive your Unique Taxpayer Reference and an activation code for your online account. Do not leave this to the last minute: the codes arrive by post and take time, so registering early in the window rather than days before 31 January avoids a scramble. If we act as your Self Assessment agent, we can handle the registration and filing for you.
Payments on account
This is the part that catches people out most often. If your Self Assessment tax bill is above a certain amount, HMRC asks you to make payments on account: advance payments towards the following year's bill, based on the assumption your income will be similar.
In practice this means that in your first year of a larger bill, you can end up paying more than you expected. Payments on account are due in two instalments: 31 January (alongside any balancing payment for the year just ended) and 31 July. Each instalment is normally half of the previous year's tax bill.
So on 31 January you might pay the balance of last year's tax plus the first payment on account for this year, which can feel like one and a half times the bill you were expecting. It is not an extra tax, just the timing of when tax is collected, but it is essential to plan for, and something we build into clients' tax planning. If your income has fallen, it is sometimes possible to apply to reduce your payments on account, though you should take care not to underpay.
What happens if you're late
HMRC applies automatic penalties for late filing, starting with a fixed penalty as soon as you miss the deadline, even if you have no tax to pay. The longer a return is outstanding, the more the penalties build up, and interest is charged on tax paid late. These penalties are avoidable with a little organisation, which is the whole case for getting ahead of the deadline rather than leaving it to late January.
Getting it off your plate
Self Assessment is manageable, but the registration window, the filing deadline and the payments on account all have to line up, and the penalties for getting it wrong are real. If you would rather not think about it, we can register you, prepare and check your return, make sure your allowable expenses and reliefs are claimed, tell you exactly what to pay and when, and file it with HMRC well before the deadline.
If you are newly self-employed, a landlord or simply unsure whether you need to file, request a consultation and we will tell you where you stand and take it from there.
Frequently asked questions
I started self-employment this year, when do I need to register?
By 5 October following the end of the tax year in which you started trading. So if you began in the tax year ending 5 April, you register by the following 5 October. Registering early is wise because HMRC sends codes by post that take time to arrive. Always confirm current dates with GOV.UK.
What are payments on account?
Advance payments towards next year's tax bill, required when your Self Assessment bill is above a set amount. They are due on 31 January and 31 July, each normally half the previous year's bill. This is why a first larger bill can feel bigger than expected, you pay the balance plus the first instalment at once.
Do I need to file if I only have a small amount of self-employed income?
There is a trading allowance below which casual self-employed income need not be reported. Above it, you generally need to register and file. Thresholds change, so check the current figure with GOV.UK or ask us if you are close to the line.
What is the penalty for filing late?
HMRC charges an automatic fixed penalty as soon as you miss the deadline, even with no tax due, and further penalties and interest build up the longer the return and payment are outstanding. They are entirely avoidable with a little planning.
Can you deal with my Self Assessment for me?
Yes. Once you authorise us as your agent, we can register you, prepare and check your return, make sure reliefs and expenses are claimed, tell you what to pay and when, and file it with HMRC ahead of the deadline. See our Self Assessment service.