United KingdomGOV.UK
HMRC sets 20-year back stop for adviser file access notices
HMRC cannot demand documents wholly predating the 20-year back stop day where they have no bearing on later tax periods; pre-April 2026 records may still be sought to test sanctionable conduct.
By Taxxa AI OyPublished 15 September 2026
Industry: Accounting, bookkeeping and auditing activities; tax consultancy
A file access notice under the tax-adviser sanctionable-conduct regime cannot require a document that originated before the back stop day, provided no part of the document has a bearing on tax periods ending on or after that day. Both conditions must hold: wholly pre-back-stop origination, and no bearing on later periods.
The back stop day is the first day of the 20-year period ending on the day the file access notice is given. The page's example makes the arithmetic concrete: a notice issued on 22 November 2026 closes a 20-year period on that date, so the back stop day is 23 November 2006, and the recipient need not provide documents wholly originating before 23 November 2006 that have no bearing on tax periods ending on or after that date.
That 20-year shield sits alongside a narrower commencement rule for the regime itself. Penalties for sanctionable conduct run only for conduct on or after 1 April 2026GOV, but a file access notice issued after that date may still request documents that existed before it, where they help determine whether the sanctionable-conduct test is met
GOV — for example, records confirming that a person was acting as a tax adviser for a taxpayer where the relationship began before 1 April 2026.
The surrounding procedure sets when such a notice may issue at all. Where HMRC has reasonable grounds to suspect a tax adviser is engaging in, or has engaged in, sanctionable conduct (Case A), it may first seek tribunal approvalGOV — a case-by-case decision, relevant for instance where the adviser has previously failed to comply. A notice to a person who is not the tax adviser, a third-party document holder, requires tribunal approval first
GOV, and that person may appeal to the tribunal on the ground that compliance would be unduly onerous
GOV. Whoever receives the notice, it must be issued in Case A or Case B circumstances.
GOV
The legal basis is Schedule 38 to the Finance Act 2012, paragraph 16 (old documents)
Legislation and paragraph 8 (when a notice may issue)Legislation.
When served with a file access notice, test each requested document against the 20-year back stop day and the tax-period-bearing exception before withholding anything, and expect HMRC to seek pre-April 2026 records where they evidence the adviser relationship.