PS1/26 is the rulebook moment for UK Basel 3.1
PS1/26 is where the Prudential Regulation Authority moved Basel 3.1 from consultation and near-final drafting into final UK rules and supervisory materials. Published on January 20, 2026, it confirms the final rule instruments, supervisory statements, statements of policy, and reporting and disclosure material that will govern implementation for PRA-regulated firms.
The most important dates are clear. Most of the Basel 3.1 package takes effect on January 1, 2027. The internal model approach for market risk takes effect later, on January 1, 2028. That split matters because it means firms cannot treat Basel 3.1 as a single once-and-done implementation. The core package lands first, while market-risk internal models run on a separate timetable.
What the final policy actually settles
The statement confirms that, aside from targeted market-risk changes made after CP17/25, the PRA has not made substantive departures from the near-final rules published earlier. Instead, PS1/26 largely finalises the package with a mixture of confirmation, clarification and technical corrections. That includes finalising the revised prudential framework across credit risk, output floor mechanics, reporting, disclosures, and related supervisory expectations.
The policy statement also confirms the broader architecture around the UK version of Basel 3.1. The PRA frames the final rules as addressing weaknesses exposed by the global financial crisis, including inadequate Pillar 1 capital in some areas and excessive variability in risk weights. At the same time, it presents the package as more risk-sensitive and more consistent, with features such as the output floor and standardised approach changes intended to create a firmer and more comparable capital baseline.
Why firms still need to pay close attention
Even where the PRA describes changes as minor, the operational effect for firms can still be meaningful. PS1/26 includes clarifications touching core implementation topics such as output-floor calculation, treatment of SME and retail exposures, real-estate revaluation and cash-flow dependence assessments, IRB model scope changes, and glossary definitions that become relevant once CRR provisions are revoked and replaced in the PRA Rulebook.
There is also a sequencing point that matters now. Because the final rules were published in January 2026 and the main implementation date is January 1, 2027, firms effectively had less than a year to move from final policy to live compliance. For institutions still refining programmes, the question is no longer “what is the PRA likely to do?” but “which rule changes, permissions, policies, data items and control changes must be fully operational by January 1, 2027, and which market-risk model elements run to January 1, 2028?”
What management teams should do now
The practical response is to use PS1/26 as the anchor document for implementation governance. Firms should map the final rules against any earlier programme assumptions built from CP16/22, PS17/23, PS9/24, PS7/25 and the 2025 delay announcement, then isolate where final clarifications alter build requirements, interpretation or sequencing. The biggest risk at this stage is not missing the existence of Basel 3.1, but missing the detail of how final PRA drafting changes operational obligations.
In our view, boards, CFOs, CROs and regulatory programme leads should focus on three things. First, confirm readiness for the January 1, 2027 live date across reporting, policy and capital processes. Second, identify any saved IRB permissions or market-risk model issues that require a separate path into 2028. Third, make sure management information distinguishes between finalised rules, still-live supervisory judgment areas and later consultations that may refine parts of the framework further.