In my experience, most offers are made Part 36. It’s quick, easy and there is less room for error (not that this is a certainty by any means).
Calderbank offers are more clunky to deal with, but they can be necessary or beneficial. The key is to know when to use what type. Overall, the main point is that usual rules of contract do not apply to Part 36 offers. For example, due to the wording of the rules, a counter offer would not result in the original Part 36 offer being reject, as you would expect in contact law.
Ability to withdraw an offer
A Part 36 offer can be withdrawn after the relevant period has expired, but the offeree can only withdraw a Part 36 offer during the relevant period with permission of the court .
With a Calderbank the offeror can withdraw at any time. This could be important for both Claimant and Defendant if they want to be able to make an offer but have the unrestricted ability to adapt to any changes in the litigation or circumstances.
It can be tactical for Defendants who want to be able to withdraw the offer at any given notice to put pressure on a Claimant to accept in a short period of time.
Staying proceedings
This is probably one of the main reasons either party would prefer to settle by Part 36. Once a Part 36 offer has been accepted, CPR 36.14(1) means the claim is automatically stayed.
All the parties need to do is advise the court and hearings, etc are automatically vacated.
When one settles by Calderbank, a Tomlin Order must be drafted to appropriately stay proceedings and vacate any future hearings. This can cause some difficulties and delays depending on how the tomlin fee is paid and processed by the court.
Settlements very close to trial may benefit from Part 36. If the terms are the same as it would be by Part 36, then consider asking the other party to make the offer Part 36 for the purposes of staying proceedings and vacating hearings swiftly and promptly.
Flexibility of terms
I’ve seen many N242A or Part 36 letters attempt to include additional terms. The difficulty with this is two fold. (1) it is not a valid Part 36 (2) it may still be a valid offer, but none of the Part 36 consequences apply.
Some Defendants want a settlement to include a non disclosure term that prevents a Claimant from discussing the claim. If one puts this into a letter with Part 36 terms, then it may be a valid offer but will not have Part 36 consequences such as staying proceedings.
Insert the non disclosure terms in an N242A and it may not form part of the offer (given the prescriptive nature of an N242A and Part 36). I once had a Defendant send me an N242A with a covering letter about an non disclosure. My client accepted the Part 36 and once the Defendant realised their error, we negotiated an extra payment for consideration for a non disclosure agreement.
Making an offer by way of Calderbank removes any potential doubt. Either party can negotiate terms and once agreed upon, can be filed once endorsed.
Simultaneous Part 36 and Calderbank
I’m surprised how rarely I see Part 36 and Calderbank made together by Defendants or Claimants.
If you haven’t seen it, it’s where a party makes a more favourable offer by Calderbank open for a short period of time and a less favourable Part 36 which is likely to have Part 36 consequences.
It is intended to provoke an acceptance promptly, which will keep costs to a minimum for your client. Although it can be used by Claimants, in my experience Defendants will have a better use for this.
Negotiations
It can be really easy to forget that usual contract law applies to Calderbank offers. Due to the self-contained nature of Part 36, contract law does not apply (Gibbon v Manchester City Council [2010] EWCA Civ 726). If a Defendant makes a Part 36 offer, the Claimant could respond with its own Part 36 and still accept the Defendant’s Part 36 offer.
When a counter offer is made, it is deemed to be rejecting the other party’s previous offer (Hyde v Wrench [1840] 49 E.R. 132 – yes I had to look this up as it as been some time). This could make the difference in tactics as to how a party responds to an offer. If the other party’s offer is lost and they are not willing to make the offer again, then this could be devastating to your client.
Is it better for a Defendant or Claimant to use Part 36 or a Calderbank?
There is no reason why either type of party should use one or the other (or both). It is most certainly the scenario that will make the difference.
For example a Defendant who is willing to pay the reasonable costs and disbursements would be better of making use of Part 36. Unless there a time limited compared with the minimal relevant period of 21 days as per Part 36, in that case – use a Calderbank.
Information
AJH Advocacy Limited, a Limited Company which is regulated by the Bar Standards Boards (entity number 190758), ceases trading on the 12th January 2026.
From the 12th January 2026 and onwards, Alec Hancock will practice as a Barrister at Magdalen Chambers in Exeter. For instructions on matters on or after 12th January 2026, please contact Magdalen Chambers via clerks@magdalenchambers.co.uk or by telephone on 01392 285 200.