EM1570 | Opening the Enquiry: Information Request: Full Enquiry - Non Business Taxpayer
From HM Revenue & Customs · Enquiry Manual
If the taxpayer is a complex director case, you should first seek to verify the income and gains declared by reference to any third party information held (for example, P11Ds).
You might also, depending on the case, ask to see
dividend vouchers
certificates of loan interest paid
private pension contribution certificates
accounts or particulars
a detailed Capital Gains computation
a copy of a property valuation
an account of the precise use made of a company asset such as a private plane.
As with a return for a business taxpayer, you should only ask to see private bank statements at this stage if you can demonstrate their relevance to the return and that you reasonably require them for the purpose of checking its accuracy.