Income Tax Self-assessment

5. Completing the Return

Collect all your tax return forms, Guidance Notes and paperwork before starting to fill in the return. Read through the return to check that you have everything you need.

5.1 Complete the return.

• Write in pencil so you can make corrections. Once you are happy with what you have written complete the return in blue or black ink.
• Only include income and gains during the tax year - from 6 April to 5 April - unless asked to do otherwise.
• Only fill in the boxes that are relevant to you. Do not worry if much of the return is left blank, but ensure that you answer all the relevant questions.Employees typically need to fill in only 40 boxes (including answers to simple questions such as 'Name of employer').The self-employed with a turnover of over £15,000 per annum will need to fill in at least 80 boxes.
• If you are unsure about an answer, give as much extra detail as possible in the 'additional information' boxes.This extra information may answer any questions the tax inspector has and prevent a HM Revenue & Customs enquiry.

5.2 Check the tax return before sending it off.

• Make sure that you sign the return (this is one of the most common mistakes).
• Make sure that you have included all the paperwork that you have been asked for.
• If you realise you have made a mistake after sending in your tax return, you can amend it within 12 months of the fixed filing date.

5.3 Wait for HM Revenue & Customs to:

• Check for mistakes and then send you a new tax calculation if necessary.
• Calculate your tax bill (if you have not done this already).
• Notify you if it plans to enquire into your return.HM Revenue & Customs will randomly select a small percentage of tax returns for enquiry. You must be notified within 12 months of the fixed filing date if HM Revenue & Customs plans to enquire into your return, provided that your return was submitted on time.

5.4 You must pay any tax owing by 31 January even if you do not receive a demand.