Basel III final reforms: what changes for banks by April 2027

For most of the last decade, Basel III in practice meant the first wave of post-crisis rules: more and better capital, buffers, the leverage ratio and the liquidity ratios. The second wave, the part that changes how risk-weighted assets are calculated, took far longer to arrive in national rulebooks. That wait is ending.

In October 2026 the Basel Committee reported that, as of 30 September 2026, three quarters of its 27 member jurisdictions had published rules adopting the final Basel III standards, and that almost all had announced that banks must apply Basel III by April 2027 or earlier.

The revised credit risk and operational risk standards and the output floor were already effective in around 85% of member jurisdictions. This guide explains what the final reforms contain, where they bite, and what banks should be settling now.

What the final reforms contain#

The Basel Committee’s December 2017 package, Basel III: Finalising post-crisis reforms, has six main parts:

• A revised standardised approach for credit risk, intended to be more robust and more risk-sensitive.
• Revisions to the internal ratings-based approach, limiting the use of the most advanced internally modelled approaches for low-default portfolios.
• A revised credit valuation adjustment (CVA) framework, removing the internally modelled approach and introducing a revised standardised approach.
• A revised standardised approach for operational risk, replacing the existing standardised approaches and the advanced measurement approaches.
• Revisions to the measurement of the leverage ratio and a leverage ratio buffer for global systemically important banks.
• An aggregate output floor, under which risk-weighted assets from internal models can be no lower than 72.5% of those calculated under the standardised approaches.

Alongside it sits the revised market risk framework, Minimum capital requirements for market risk, published by the Basel Committee in January 2019 and often called the FRTB. It clarifies which exposures are subject to market risk capital, revises the standardised approach and changes how supervisors assess whether individual trading desks may use internal models.

Why the timetable moved#

The 2017 package was originally due to take effect from 1 January 2022. In March 2020 the Group of Governors and Heads of Supervision, the Basel Committee’s oversight body, deferred the implementation date of the December 2017 standards and the revised market risk framework by one year, to 1 January 2023, and extended the transitional arrangements for the output floor to 1 January 2028.

Member jurisdictions have since adopted the rules on their own timetables, which is why a bank’s effective date depends on where it is supervised.

Where the reforms bite#

For banks on the standardised approach, the revised credit risk rules change risk weights across the book. Real estate exposures are the clearest example: weights depend on the loan-to-value ratio, and exposures that depend materially on the cash flows of the property are treated separately. Because the revision runs across the whole standardised approach, it reaches pricing and product decisions, not just reporting.

For banks that use internal models, the output floor changes the question. A model can still produce a lower figure, but the capital requirement cannot fall below 72.5% of the standardised result, so every modelled portfolio now needs a reliable standardised calculation beside it. The Basel Committee also requires banks to disclose their risk-weighted assets based on the standardised approaches.

Because the floor ties every internal model to a standardised figure, the standardised approach can now constrain capital at banks that use models, not only at those on the standardised approach.

Operational risk moves to a single standardised approach based on a defined measure of the bank’s business, the Business Indicator, in place of the earlier menu that included internal models. CVA capital no longer has an internally modelled route.

Where banks go wrong#

• Treating the reforms as a reporting change. Higher or different risk weights reach pricing, limits and the products a bank chooses to offer.
• Running the standardised calculation as an afterthought in a bank that uses models. Under the floor it can become the binding number.
• Underestimating data. Loan-to-value ratios, property valuations, rating information and counterparty classifications all need to be captured at the right level.
• Planning capital on the current rules. A capital plan that crosses the effective date has to show the requirement under the new rules, including any transitional arrangements the supervisor applies.
• Reading the Basel text instead of the local rule. Jurisdictions adopt the standards with their own choices and timetables, and the binding rule is the national one.

What to settle now#

1. Confirm the effective date, transitional arrangements and national choices that apply to each entity in the group.
2. Run the revised standardised calculations in parallel with the current ones, portfolio by portfolio, and explain the differences.
3. For banks that use models, measure the distance to the output floor and the portfolios that drive it.
4. Close the data gaps the new risk weights expose, starting with real estate and corporate exposures.
5. Re-base the capital plan, risk appetite limits and product pricing on the new requirement, and brief the board on the result.

The Basel III Final Reforms & Capital Planning programme works through the revised approaches and their effect on the capital plan over two days, and The Basel IV Executive Masterclass takes the same reforms to the executive level: capital optimisation, risk-weighted asset management and governance. For lenders with large property books, Real Estate & Mortgage Finance covers how the loan-to-value approach changes real estate lending.