There is a legal requirement to retain records relating to the Self Assessment Tax Return. HMRC guidelines relating to tax records can be found at GOV.UK Website
Taxpayers who do not carry on a trade are required to retain records of income and capital gains until the later of:
a) 22 months from the end of the tax year.
b)the date on which the enquiry window closes.
c)the date on which an enquiry into the Return is closed.
Taxpayers who are self-employed, in partnership or who have income from property must retain records until the latest of:
a) Five years and 10 months after the end of the tax year.
b) The sixth anniversary of the end of the accounting period
c) The date on which the enquiry window closes
d) The date on which an enquiry into the Return is closed.
Penalties may be charged for the failure to retain proper records. The maximum penalty is £3,000 for each failure to maintain records sufficient to support entries on the Return.
Most businesses, will be required to keep records digitally to support the quarterly reporting required under the Making Tax Digita(MTD) proposals by using a software package.
The latest timetable for MTD applies to those businesses and landlords with turnover which exceeds the VAT threshold.
Those businesses and landlords with turnover below the current VAT threshold will not be required to keep digital records or report to HMRC on a quarterly basis.