This Practice Note considers section 32(1)(c) of the Limitation Act 1980 (LA 1980), which may apply where the action is for relief from the consequences of a mistake. Where it applies, the limitation period does not begin to run until the claimant has discovered the mistake, or could with reasonable diligence have discovered it. This means that time begins to run when the claimant knows, or could with reasonable diligence know enough to recognise that it has a worthwhile claim. The provision has received less judicial attention than the other limbs of LA 1980, s 32(1), but its application and scope have been clarified in important House of Lords and Supreme Court decisions, particularly in tax claims for recovery of taxes incorrectly paid or paid under legislation later found to be unlawful under EU law. For an overview of LA 1980, s 32 and guidance on issues common to each limb of the provision, including reasonable diligence—see Practice Note: Limitation—fraud, deliberate concealment and mistake. See also the following Practice Notes for related LA 1980, s 32 content: