Read This With One Limit in Mind
Attersley concerned the pre-October 2023 fixed costs regime under Section IIIA of Part 45, applicable to a claim that left the RTA Protocol in 2018. It is not a blanket answer to questions arising under the extended fixed recoverable costs regime that followed, and it should not be cited as one.
What travels beyond the transitional facts is the principle about which dategoverns, and that is the reason this note exists.
The Short Point
Late acceptance does not let a party rewrite the costs regime that applied when the relevant period expired.
What Happened
Attersley v UK Insurance Limited [2026] EWCA Civ 217, Court of Appeal, 24 March 2026, judgment of Lord Justice Miles. The chronology does the work, so it is worth setting out in full:
- 9 March 2018 — road traffic accident.
- 19 March 2018 — Claim Notification Form under the RTA Protocol.
- 9 April 2018 — claim exits the Protocol at the defendant’s request.
- 29 April 2019 — liability admitted.
- 13 February 2021 — Part 7 proceedings issued.
- 4 March 2021 — defendant’s Part 36 offer of £45,000.
- 25 March 2021 — the relevant period expires.
- 5 January 2022 — the claim is allocated to the multi-track.
- 8 July 2022 — the offer is accepted, roughly 16 months after expiry.
What the Claimant Argued
That by the date of acceptance the claim was a multi-track claim, so the fixed costs regime had been displaced and CPR 36.13 applied, entitling her to costs on the standard basis.
It is not a fanciful argument. By July 2022 the claim genuinely was on the multi-track, and acceptance is the event that triggers the costs consequences.
Why It Failed
The Court of Appeal held that CPR 36.20 governed, because the offer had been made before allocation and the relevant period had expired before allocation. Acceptance afterwards did not change that.
The reasoning is the part worth keeping. Lord Justice Miles described Part 36 as a “self-contained procedural code” of which “certainty is one of its essential features”. A rule under which later procedural events reached back and rewrote costs consequences already fixed would destroy exactly that certainty — a party deciding whether to accept could not know what accepting would mean.
What Claimant Firms Should Actually Take From It
Stop treating acceptance as the only date that matters. A Part 36 costs analysis needs six dates, and most files record two:
- the date of the offer;
- the expiry of the relevant period;
- the costs regime in force at that expiry;
- the allocation date;
- the acceptance date; and
- any later procedural change.
Where those dates straddle a change of track or of regime, the order they fall in decides the outcome. The practical mechanics of late acceptance are set out in our guide to Part 36 late acceptance and the CPR 36.17 consequences.
What Attersley Does Not Decide
The court expressly declined to decide other timing combinations, and noted that the drafting does not deal with them with complete clarity. Two are left open:
- where the Part 36 offer is made after multi-track allocation; and
- where the offer is made before allocation but the relevant period expires after it.
So Attersley closes one timing route rather than settling the field. A file whose dates fall into either gap is not answered by this decision, and anyone saying otherwise has read the headline and not the judgment.
How DMD Costs Can Help
We prepare and negotiate standard-basis claimant costs for solicitor firms. Where a Part 36 offer sits behind a costs dispute, the chronology usually decides it, and it is worth building before the bill rather than after Points of Dispute arrive. Send us the file and we will confirm the fixed fee before any work begins.
A Note on Sources
Citation, court, date, the constitution, the chronology and the quoted wording were checked against independent reports of the judgment before this note was written.