FCA maps transition to new transaction reporting rules for 2028

The Financial Conduct Authority (FCA) has opened a new consultation setting out how it plans to move UK investment firms, trading venues and reporting infrastructure onto a replacement transaction reporting regime by 3 April 2028. Consultation paper CP26/34, published on 2 October 2026, does not reopen the underlying policy — that was finalised in PS26/15 in August 2026 — but it proposes the guidance, draft data schemas and transitional rules that firms will need to actually build against. Responses are due by 6 November 2026.

The timetable matters because the commencement date is fixed, not staged: 3 April 2028 is confirmed as the day the new MAR 13, MAR 14 and MAR 15 regime — finalised in PS26/15 — takes effect. Under proposals set out in CP26/34, the FCA's systems would switch over in full on that date, with current UK Markets in Financial Instruments Regulation (UK MiFIR) reporting formats no longer accepted and the new MAR formats taking their place. Firms, approved reporting mechanisms (ARMs) and trading venues that submit transaction reports, instrument reference data or order book data to the FCA all need to be ready for that date, and CP26/34 is the FCA's attempt to tell them, well in advance, what "ready" will mean.

Who this affects

CP26/34 is aimed squarely at the firms and infrastructure providers that currently handle transaction reporting under UK MiFIR: investment firms, operators of trading venues, ARMs, trade associations and other participants that submit transaction reports, instrument reference data or order book data to the FCA. Investment firms typically report either through an ARM or via a direct connection to the FCA's Market Data Processor; trading venues submit market data either directly or through a third party. Any of these routes could be affected by the schema and validation changes the FCA has proposed, so firms should check which of their reporting vendors and internal interfaces sit in scope.

The implementation timetable

The FCA has laid out a sequence of steps between now and the 2028 go-live, several of which are still in motion:

The draft schemas and validation rules published alongside CP26/34 remain under development. The FCA has not yet said when this version will be available for testing in the Market Data Processor Industry Test Environment, which is a gap firms should flag if it affects their build and testing plans. The final field structure, validation rules and any supporting XML representations may still change after the FCA reviews consultation feedback; CP26/34 specifically asks firms how they currently use the existing XML representations, which suggests their future is not yet settled either.

The proposed Transaction Reporting User Pack is intended to consolidate the retained EU non-legislative material, FCA clarifications and reporting examples that firms currently rely on into a single document aligned to the new regime. Until 3 April 2028, the relevant existing EU Level 3 materials — pre-existing EU non-legislative guidance issued by the European Securities and Markets Authority — continue to guide compliance with the current UK regime. The FCA proposes to replace and withdraw that material only once the new regime takes effect, so firms do not lose their existing reference guidance early.

How the cutover is proposed to work

CP26/34 sets out proposed transitional mechanics for the handful of days either side of 3 April 2028, since transactions executed before the cutover will not all have been reported by the time the new system goes live.

For transactions executed from 00:00:00 UTC on 31 March 2028 through 23:59:59 UTC on 2 April 2028, a firm could use the existing UK MiFIR format provided it submits the report before 3 April 2028. Any submission made on or after 3 April 2028 — even for a transaction executed in that window — would instead need to use the MAR 14 format. The same proposed approach would apply to instrument reference data and to Article 26(5) reports from qualifying trading venues.

Firms would not be required to reformat historical order and transaction records into the new MAR 13 format; pre-cutover records could be retained in whatever format applied when the order was submitted or the transaction executed. Corrections are treated differently, however: once 3 April 2028 passes, any correction submitted to the FCA — including a correction to a pre-cutover transaction or reference data record — would have to comply with MAR 13, MAR 14 and MAR 15. The FCA proposes that firms would not need to backfill information that was not required under the rules in force when the original event occurred, which limits the scope of retrospective work.

Separately, the FCA is considering removing instruments that are tradeable only on EU trading venues from the FCA's Financial Instrument Reference Data System (FIRDS) ahead of the 3 April 2028 cutover. This is contingent on HM Treasury first amending the underlying legislation, and CP26/34 does not give a date for either step. Firms that rely on FIRDS for scope determination should treat this as an open question rather than a confirmed change.

The consultation also proposes consequential amendments across the FCA Handbook, replacing references to UK MiFIR Articles 25 and 26 and their associated technical standards with references to MAR 13, MAR 14 and MAR 15. These updates touch the Glossary and chapters including the Conduct of Business sourcebook, the Market Conduct sourcebook, the Recognised Investment Exchanges sourcebook and the Senior Management Arrangements, Systems and Controls sourcebook. The FCA's position is that the reference changes themselves should not require firms to change their processes, though firms may want to review record-keeping where specific data elements have been removed from scope.

What the proposed guidance covers

Alongside the transitional rules, CP26/34 consults on early guidance intended to feed into the future User Pack. The seven areas covered are:

• Client indicator fields
• Conditional single-sided reporting
• The meaning of a transaction
• Branch execution
• Equity swaps
• Strike price
• Package transactions

These are proposals, not finished guidance — the FCA intends to consult further on the full User Pack in Q1 2027 before publishing a final version by 3 April 2027. Firms with views on how these seven areas should work in practice have until 6 November 2026 to respond to CP26/34 itself.

What firms need to prepare now

Because the schemas and guidance are still draft, the practical work for firms before 6 November 2026 is less about building final systems and more about identifying gaps and risks. Based on what CP26/34 and the Market Data Processor materials set out, that includes reviewing the draft schemas and validation rules against existing reporting logic, mapping which transaction types and data elements will move between UK MiFIR formats and the new MAR 13/14/15 structures, and identifying which reporting vendors, ARMs or direct Market Data Processor connections will need rebuilding. Firms should also consider how they will handle the 31 March to 2 April 2028 cutover window operationally, and how post-cutover corrections to older reports will be resourced given the new compliance requirement to use MAR 13, MAR 14 and MAR 15 formats even for historical events.

None of this changes firms' underlying transaction-reporting obligations. The proposals in CP26/34 affect the technical means of meeting those obligations — the schemas, formats and guidance used — rather than the requirement to report accurately and on time.

Context: what PS26/15 already finalised

CP26/34 sits on top of final rules the FCA made in PS26/15, published on 3 August 2026, and does not revisit them. Those final changes include cutting the number of transaction-report fields from 65 to 52, removing foreign-exchange derivatives from reporting scope — a change the FCA says should benefit more than 400 UK firms — removing around 7 million instruments tradeable only on EU venues from the future reporting scope, and reducing the default back-reporting period for corrections from five years to three years, a change the FCA estimates will cut the number of reports requiring resubmission by a third. The FCA has estimated that the industry's current annual transaction-reporting cost of roughly £493m will fall to approximately £385m once the new regime is in force, a net annual saving of about £108m. These are the regulator's own estimates and relate to the finalised policy rather than to the implementation proposals in CP26/34.

What to watch next

Firms, trade bodies and reporting providers with views on the draft schemas, the seven guidance areas or the proposed transitional arrangements have until 6 November 2026 to respond to CP26/34 through the FCA's consultation process. Several practical details remain open, including when the draft schemas will be available for testing in the Industry Test Environment and whether HM Treasury will amend the legislation needed for early removal of EU-only instruments from FCA FIRDS. Neither question has a stated resolution path in CP26/34; firms should watch for further FCA technical updates on the Market Data Processor webpage and for any HM Treasury legislative action, rather than assume the Q1 2027 User Pack consultation will settle them. After that, the next formal milestone is the FCA's planned Q1 2027 consultation on the full Transaction Reporting User Pack, ahead of its targeted final publication by 3 April 2027 — a year before the regime itself takes effect on 3 April 2028. The full consultation paper, the draft schemas and the Market Data Processor updates are available directly from the FCA's website.