UK Property Tax Specialists
and Chartered Accountants

01902 711 370

0800 907 8633

Menu +

Self Assessment – How it works

Self Assessment - How it works

Self Assessment - How it works

Let’s explain by way of an example: Sarah started to let a property in September 2019 for £15,000 with allowable expenses of £3,000 per annum. She does not have a mortgage on the property. She has other income which uses her personal allowance so the income will all be taxed at the higher rate (currently 40%). She has not had to complete a self-assessment tax return before.


What are her responsibilities?

Before 5th October 2020
She must inform HMRC that she has a source of untaxed income within six months of the end of the relevant tax year. As Sarah’s rental income profits are first received in the tax year ending on 5th April 2020 she must notify no later than 5th October 2020. HMRC have produced form SA1 to enable taxpayers to notify that they have a liability which can be found on the Government website.


Before 31st October 2020 (optional)
If she wants to complete a paper tax return and/or HMRC to calculate her tax liability, the paper 2019/20 tax return must be filed by 31st October 2020. There is a £100 penalty if the paper return is filed after this date.


Before 30th December 2020 (optional)
If Sarah’s liability is less than £3,000 and she wants the liability to be included in her PAYE code for 2021/22 (see below), she must either have filed a paper return by 31st October 2020 or filed an electronic return before 30th December 2020.

Before 31st January 2021
If she has not filed a paper tax return by 31st October 2020, she must file a tax return electronically by 31st January 2021 or she will be liable to a penalty of £100. (See "What if you are late?" below). There are certain individuals (e.g. politically sensitive individuals) who are not allowed to file electronically so they may have to file a paper return by this date instead.


What are Sarah’s tax liabilities?

Assuming that the income carries on at the same rate until at least 5th April 2020, her liabilities will be:

Tax Year            Tax due

2019/20               £2,800         (Profits to 05/04/20 7,000 @ 40%)

2020/21               £4,800         (Annual Profits of 12,000 @ 40%)


When is her tax due?

Is Sarah employed?
If Sarah is employed, she will be paying income tax under Pay As You Earn (PAYE). HMRC do try to include estimates for rental income in PAYE codes which means that the tax can be collected up to two years earlier than necessary. We, therefore, advise that you do not ask HMRC to have an estimate included in your code.

Sarah’s tax liability for 2019/20 will be £2,800 and provided her 2020 self-assessment tax return is filed before 30th December 2020, this liability can be included in her code for 2021/22 as it is less than £3,000. This means that the liability would be collected in instalments in the year ended 5th April 2022 rather than the year ended 5th April 2020 if HMRC had included an estimate of the income in the 2019/20 PAYE code.

If the self-assessment liability for any tax year is more than £3,000, it cannot be included in the PAYE code. So Sarah would not be able to have her liability for 2020/21 of £4,800 included in her code for 2022/23. Therefore, she would have a liability of £7,200 to pay on 31st January 2022 in the same year as the £2,800 for 2019/20 was being collected through her code (see below). It is therefore important that cash is kept to one side for any liabilities.


If Sarah is not employed or she has a liability of more than £3,000:
If the net liability is less than £1,000 or 20% of the total tax and Class 4 national insurance before any tax deducted is taken into account, then the liabilities are due on 31st January following the end of the tax year and there are no payments on account. So Sarah would have to pay £2,800 on 31st January 2021 and £4,800 on 31st January 2022 if she met the 20% criteria.

If neither condition is met, payments on account are due for the following tax year of half of the previous year’s income tax and Class 4 NIC liability on 31st January in the following tax year and another half six months later on 31st July. If the liability of the following year increases then the balance is due on the following 31st January and the payments on account increase for the next year. If the liability for the following year decreases, then there would be a repayment of the difference and the payments on account reduce for the next year. A claim can be made to reduce the payments on account if a reduction in the liability is expected, for instance, if the rental income had ceased. If the payments are reduced by too much, there is an interest charge on the overclaim. In the first year in which payments on account are due, there is effectively a payment of one and a half years tax at once. This is best shown using Sarah’s liabilities as an illustration:

Date DueTax YearTax Liability
Tax Liability
(2019/20 in PAYE Code)
2019/20 Total Liability2,800-
2020/21 1st POA (1/2 x 2,800)1,400-
31st January 20214,200-
2020/21 2nd POA (1/2 x 2,800)1,400-
31st July 20211,400-
2020/21 balance (4800 - (2 x 1400)2,0004,800
2021/22 1st POA (1/2 x 4,800)2,4002,400
31st January 20224,4007.200
2021/22 2nd POA (1/2 x 4,800)2,4002,400
31st July 20222,4002,400

If Sarah’s income and tax liability were to stay the same then her payments would remain at £2,400 on 31st January and 31st July each year thereafter because the payments on account would match the liability. This is unlikely in practice, but if the income levels are similar each year, the payments in January and July are likely to be similar after the first three years.

Because of the coronavirus pandemic, the Government has announced that the second payment on account for 2019/20 due on 31st July 2020 can be deferred until 31st January 2021.


Capital Gains Tax

If there is a Capital Gains Tax liability, it is added to the income tax liability and is due on 31st January following the end of the year of assessment. It is not taken into account when calculating the payments on account and does not need to be taken into account when considering whether to reduce the payments on account in any tax year.


What if you are late?

There is an automatic non-refundable penalty of £100 if the return is not filed by the due date (usually 31st January following the end of the tax year). If there is a reasonable excuse, the penalties will be waived. If the return is more than three months overdue, there is a penalty of £10 for each further day that the return is late up to a maximum of 90 days. If the return is more than six months late there will be a further penalty of £300 or 5% of the liability if this is higher. If the return is filed more than twelve months after the filing deadline (i.e. 31st January 22 months after the end of the tax year) there will be a further penalty of £300 or 5% of the liability if this is higher in addition to the penalty due for the previous 31st July. In serious cases, the penalty may be up to 100% of the tax due. If you do not pay on time, interest runs on any amount paid late. There is also a 5% penalty if the liability for the previous tax year is not paid by 30 days after 31st January following that tax year and a further 5% penalty if it is not paid by the 31st July after that. If the tax is not paid by the following 31st January then there will be a third 5% penalty.

The penalties are costly and it is vital that all taxpayers ensure that their returns are filed on time.

What you do if you cannot pay?

Try to make an arrangement with HMRC. There is currently a Business Payment Support Service Helpline their contact number is 0300 200 3835.

© Thandi Nicholls Ltd 2020 All Rights Reserved - The above articles are provided for guidance only and may not cover your personal circumstances so you should not rely on them. It is important that you seek appropriate professional advice which takes into account your personal circumstances where you can provide the full facts of the case and all documents related to your case. Thandi Nicholls Ltd t/a, K Nicholls FCA or S Thandi cannot be held responsible for the consequences of any action or the consequences of deciding not to act.

Contact us

The Next Step... Get in touch

Call us, email us or ask us to contact you

By sending us a message via our website, you are agreeing for us to contact you via email or phone to answer your enquiry. Please read our Privacy Policy for more information
I agree