This Practice Note identifies the different forms which an offer to settle a dispute may take, from open offer letters and Calderbank (without prejudice save as to costs) (WPSAC) letters to Part 36 offer letters; examining their respective advantages and disadvantages, their impact on costs liability and how to draft such offer letters. For further guidance on without prejudice communications, including Calderbank (WPSAC) letters, see Practice Notes: Without prejudice communications, Without prejudice explained and Without prejudice—exceptions to protection from admissibility. Although this Practice Note briefly summarises the key aspects of Part 36 offers to settle, for full guidance on all aspects of making, receiving, varying, accepting and rejecting a Part 36 offer and detailed precedents, see: Part 36 offers—overview. For guidance on how to make an offer or record a settlement and on drafting settlement agreements, see Practice Notes: • Settling disputes—how to document a settlement • Settling disputes—drafting the settlement agreement • How to make a genuine without prejudice offer For guidance on why, when and how to settle disputes,