Дополнительная информация о том, что имеется в виду под business assurance применительно к HMRC:

A clear tax policy that is supported by operating procedures that have been reviewed by the internal audit/business assurance department.
http://www.hmrc.gov.uk/lbo/tax-in-the-boardroom.htm

HMRC Business Assurance Visits

If the Taxman calls you and suggests he should visit your business as part of their Business Assurance programme, should you agree?

The Taxman is offering to visit new businesses to help them understand what sort of business records they should be keeping. During the visit the Tax Officer will ask the business owner how they record sales, purchases and expenses, how they handle cash, and how they calculate and record drawings or remuneration. Your answers to these questions will be recorded by the Taxman and amount to a “Compliance check”, which is another way of saying “enquiry into your tax affairs”
http://www.accountancyextra.co.uk/blog/index.php/2010/08/06/...

Имхо, как и обычно.