EIM42205 | Employment income: basis of assessment for general earnings:

For years before 1989/90 the statutory basis of assessment for earnings from an office or employment was the earnings basis - people were to be taxed on the remuneration earned in the year irrespective of when it was paid. In practice, taxpayers were often assessed on an “accounts basis”, or a receipts basis. Guidance on years before 1989/90 is not included in this manual.

Do not in any circumstances continue or adopt an “earnings” or “accounts” basis of assessment for any year after 1989/90.