This Practice Note provides guidance on discharging a contractual debt. It explains how to establish when a debt is due for payment, what amounts to discharge, the effect of part payment of a debt (including discussion of the rule in Pinnel’s case, payment by instalments, compromise agreements and promissory estoppel), the role of third parties, how payments are appropriated to multiple debts, the defence of tender before claim and the effect of illegality on payment of a debt. For guidance on precisely what a claim in debt is, see Practice Note: Debt claims. For practical guidance on bringing debt claims, see: • Practice Note: Starting a contractual debt claim—a practical guide • Practice Note: Pleading debt claims—worked hypothetical examples • Starting a contractual debt claim—checklist • Responding to a contractual debt claim—checklist See also Precedents: • Letter of claim—contractual debt claim • Letter of claim—contractual debt claim—in compliance with the Pre-Action Protocol for Debt Claims • Covering letter to accompany Reply Form in response to letter of claim sent pursuant to the Pre-Action Protocol for Debt Claims • Particulars