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HMRC internal manual

Self Assessment Manual

Returns: individuals returns: accounting periods and basis periods: individuals

Accounting Period

This is the period to which the details provided of income and expenses, tax adjustments and balance sheet, relate.

Relevant boxes (8 and 9 on the Self-employment (full) page SEF 1) should be completed by the taxpayer to indicate the start and end dates of the accounting period used.

On the Short Tax Return (SA200), box 3.4 should be completed to enter the end date of the accounting period used by the taxpayer to complete the details of self-employment income. The start date of the period is not requested.

Basis Period

This is the period used to identify the profits which are taxable in any particular tax year (normally the 12-month period up to the annual accounting date).

Relevant boxes (64 and 65 on the Self-employment (full) page SEF 4) should be completed by the taxpayer to indicate the start and end dates of the income tax basis period.

In form SA200 cases you should only complete boxes 3.12A and 3.12B, to indicate the start and end dates of the income tax basis period, where an entry has been made on the return in box 3.2 or 3.3.

Capture of Dates

In a few cases, the two sets of boxes (SEF 1 at 8 / 9 and SEF 4 at 64 / 65) may properly contain different dates because the accounting period and basis period will not always be the same. However, in most cases the two sets of dates are the same.

Note: It is therefore not considered reasonable to reject a return where dates are given in one set of boxes but not repeated in the other set of boxes. 

  • Where all four boxes are blank you should consider whether you hold any information that enables you to complete these boxes on screen. If you do not, you can treat the return as unsatisfactory and tell the taxpayer that you need these date boxes completed
  • Where only one set of dates is completed you can use those dates to complete the other set of boxes. You should not reject the return as unsatisfactory unless you have another reason for doing so

Further advice on unsatisfactory returns is available in subject ‘Unsatisfactory Individuals Returns’ (SAM121260).