UK: Manuals for advance tax certainty service (ATCS), mandatory tax adviser registration
New ATCS for very large UK investment projects begins July 1, 2026.
HMRC published final guidance on its new advance tax certainty service (ATCS) for very large UK investment projects, which begins July 1, 2026, in the form of an ATCS manual, outlining the scope, process, and eligibility requirements of the ATCS. The manual largely follows previously published draft guidance, but does add further information on how a “low-risk” view may be obtained on the potential application to the investment project of the unallowable purpose rules in the loan relationships and derivative contracts regimes.
HMRC on June 1, 2026, also published final guidance on the new requirement for tax advisers to register with HMRC, in the form of a new manual. The registration requirement may apply quite widely, capturing some in-house tax teams, law firms, financial institutions, asset managers, and family offices. The registration process opened on May 18, 2026, and is currently open for “new tax advisers, or those interacting with HMRC without an agent services account (ASA), self assessment, or corporation tax account.”
Read a June 2026 report prepared by the KPMG member firm in the UK