Without prejudice save as to costs | UK Insurance Wiki

Category: Claims handling · Reviewed by Taylor Watts, Broker · New Business · Last reviewed 2026-06-11

“Without prejudice save as to costs” (WPSAC) is a hybrid privilege qualifier that protects the communication from disclosure on the substantive issues while preserving the right to refer to it after the substantive decision on the question of costs — the standard formulation for Calderbank offers.

Definition

The WPSAC qualifier is the second of the without-prejudice family. Pure without-prejudice protection prevents the communication being used in evidence at all. WPSAC protection prevents use during the substantive trial but allows reference once the substantive question has been decided, for the purpose of the court’s costs decision.

In commercial dispute practice, WPSAC is more commonly used than pure without prejudice for formal settlement offers. The reason: a settlement offer is most useful if it can be referred to on costs if rejected. WPSAC achieves that effect outside the strict Part 36 framework.

Legal / Regulatory basis

The framework is the same as for pure without prejudice — Rush & Tompkins v GLC [1989] AC 1280, Unilever v Procter & Gamble [2000] 1 WLR 2436, Ofulue v Bossert [2009] UKHL 16 — with the specific recognition that the “save as to costs” qualifier preserves the right to refer on costs.

The case law has confirmed:

• The “save as to costs” reservation is effective and the courts respect it.
• The reservation must be clearly expressed; mere “without prejudice” without the qualifier does not preserve costs reference.
• The communication must be a genuine settlement offer to attract the protection.
• The exceptions to the without-prejudice rule (the Unilever categories) apply equally to WPSAC communications.

CPR 44.2(4)(c) expressly requires the court to take account of admissible offers to settle when making costs orders. WPSAC offers are admissible on this question.

How it works in practice

A WPSAC letter is the standard form for Calderbank offers and other settlement proposals where the offeror wants the costs consequences without engaging the Part 36 architecture.

The letter is marked “Without prejudice save as to costs” at the top. It sets out the offer terms (the amount, the conditions, the deadline) and is sent to the opposing party. The recipient can accept or reject.

If accepted, the matter settles on the terms of the offer. If rejected and the matter goes to judgment:

• The letter is not adduced at the substantive trial.
• After judgment, the parties make written or oral submissions on costs.
• The WPSAC letter is then disclosed and considered.
• If the recipient should have accepted (the eventual outcome is worse than the offer), the court typically orders the recipient to pay the offeror’s costs from the date of the offer (or the expiry of any acceptance window).

The cost consequences are discretionary, unlike Part 36. The court considers the reasonableness of the offer, the timing, the parties’ conduct and any other relevant factor.

WPSAC offers are particularly useful where:

• The offer is on unusual terms not easily fitting Part 36.
• The offer is made very early in the dispute, before Part 36 timing rules optimally engage.
• The offer is conditional on external events.
• The offer is from a party not formally engaged in proceedings (an insurer to an opposing party, before the policyholder has been named).

For insurance defence, WPSAC offers are a common tool alongside Part 36. A typical sequence: pre-action WPSAC offer; Part 36 offer once proceedings are issued; further WPSAC offer (sometimes called an “improved Calderbank”) as the matter develops; Part 36 acceptance or final settlement at JSM/mediation.

Common variations

“Calderbank offer” — the historical phrase for a WPSAC offer.

“Time-limited WPSAC” — offer open for a defined period after which it is withdrawn.

“Conditional WPSAC” — offer contingent on an external event.

“Improved WPSAC” — a later offer at higher value, supplementing an earlier offer.

“WPSAC counter-offer” — the recipient’s own settlement proposal.

Example

A defendant’s PI insurer makes a WPSAC offer at £450,000 inclusive of costs eight months before trial. The claimant rejects. The matter proceeds to trial; judgment for £390,000 inclusive of damages and pre-trial interest.

Costs hearing: the WPSAC letter is referred to. The claimant has failed to beat the offer by £60,000. The court holds that the claimant should have accepted the offer; the rejection was unreasonable in light of counsel’s preliminary view available at the time.

Costs order: the defendant’s costs from the date of the WPSAC offer (£140,000) are awarded against the claimant on the standard basis. The claimant’s costs from the same date (£155,000) are not recoverable from the defendant.

Net economic outcome for the claimant: damages £390,000 plus pre-WPSAC costs (recovered) minus post-WPSAC own costs (£155,000) minus post-WPSAC defendant’s costs (£140,000) = £390,000 + costs - £295,000 = approximately £170,000 net.

If the claimant had accepted the WPSAC offer at £450,000 inclusive: net recovery £450,000 (the costs would have been within the inclusive figure or paid on top depending on the offer’s wording).

The WPSAC offer reduced the claimant’s net recovery by approximately £280,000.

See also

• Calderbank offer
• Part 36 offer
• Without prejudice negotiation
• Sealed offer
• Tomlin order

References

1. Calderbank v Calderbank [1976] Fam 93.
2. Rush & Tompkins Ltd v Greater London Council [1989] AC 1280.
3. Unilever plc v Procter & Gamble Co [2000] 1 WLR 2436.
4. Civil Procedure Rules, Part 44.2(4)(c).

Last reviewed

By Matt Bartlett, Director, on 2026-06-11. Next review: 2026-12-11.

This entry is part of the Apex Insurance Wiki. Last reviewed by Matt Bartlett on 2026-06-11. Apex Insurance Brokers Limited, FCA FRN 724952, Companies House 07014570. Not regulated advice — consult your broker on your specific position.