If you are self employed or a company director, you will have to fill in and return an annual self assessment. This can seem like a daunting prospect – but, if you are organised and don’t leave it to the last minute, completing your self assessment should not be too much work.

What are the self assessment deadlines?

To begin with you should learn the most important self assessment dates.

• At the beginning of each tax year you will receive notice that you must fill in your self assessment for the tax year that has just passed. If you normally do it on paper you will receive a self assessment form. If you normally file online you will just receive a letter.
• 31 October – if you are completing a paper self assessment you must return it by this date. HMRC will then calculate your tax for you. If you miss this deadline you will receive a £100 fine.
• 30 December - you must file your application online by this date if you want HMRC to collect your tax through your tax code. This is not always possible for self employed people.
• 31 January – this is the last date by which you can file your return online. If you miss this deadline you will receive a £100 fine. 31 January is also the date by which you must pay any tax you owe if you were sent a notice to complete a self assessment before the previous 31 October. Interest will start to accrue if you do not pay the balance by this point. You will also have to make your first payment on account for the current tax year where applicable.
• 28 February – if you still have not paid your balance by this point you will receive an automatic 5 per cent surcharge.
• 31 July - the second payment on account is due on this date. If you have not cleared your balance you will also receive a second 5 per cent surcharge.

What records must I keep for self assessment?

You have a legal obligation to keep certain records. You will also need these records when completing your self assessment. The most important of these include:

• bank or building society statements;
• payslips;
• dividend vouchers or dividend counterfoils if you are paying yourself dividends;
• records of any sales (invoices, for example);
• invoices for any business purchases or business expenses;
• business bank account statements.

You must retain these records for at least 22 months after the end of the relevant tax year.

How do I fill in my self assessment?

If you normally fill in your self assessment by hand, or if you have not filled in a self assessment before, HMRC will send you a paper form to fill in. This basically consists of a series of numbered boxes into which you must add information about your income and outgoings. There are instructions at the end of the form to tell you how to add up these boxes.

Most people find it easier to complete the self assessment online. You can register for online self assessment on the HMRC website by clicking here.