Self-assessment is the process HMRC uses to collect income tax outside of wages, pensions and savings. People and businesses with other income need to file a tax return each year.

Income received during the financial year (between 5 April and 6 April) must be reported in a tax return, which you fill in after the end of the tax year it applies to.

There are 2 deadlines to send in your tax return:

  • 31 October (paper form)
  • 31 January (online).

This blog post will touch on the self-assessment paper tax return and requirements to completing it on time.


The first step before completing your tax return is registering for self-assessment. Registration must be completed by the 5 October.

The registration process is done online and once completed you’ll receive a 10-digit unique taxpayer reference (UTR) and an activation code through the post within 10 working days.

You will need these details to log in to your online account.

If you’re registering a partnership for self-assessment, you need to complete form SA400.

Remember to have your UTR number or VAT reference number added to your business tax account.


There are records you need to have to hand when filling out your tax return. These include:

  • P60, P45 and P11D forms
  • business records or profit/loss account (if you work for yourself)
  • bank statements
  • personal pension contributions certificates.


For completing your tax return on paper, you will need to fill in form SA100.

If you have other types of income, you may need to fill in more sections known as ‘supplementary pages’.

These sections are:

Filing your return

Once you’ve completed your forms you need to submit your tax return through HMRC’s online service.

Remember to have your UTR number at and ensure your online account is activated well in advance of the deadline to avoid any last-minute panics.

The next deadline to send your paper tax return is no later than 31 October 2017.

Once submitted, HMRC will calculate the amount tax you need to pay for the tax year.

Contact us

If you would like further advice on completing your paper tax return on time, don’t hesitate to get in touch as we can help you with any aspect of self-assessment.

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