This Practice Note is about: • a taxpayer’s right to receive interest on repayments of overpaid tax, whether under a statutory regime, the common law (and specifically the law of restitution), or EU law, retained EU law or assimilated law • the corporation tax charge on restitution interest, and • for tax that was overpaid before 31 December 2020, EU law on whether overpaid tax may give rise to a right to damages This Practice Note includes references to EU-derived law and case law. The UK ceased to be an EU Member State on 31 January 2020. On this date the UK entered an implementation period (IP), during which it continued to be treated as a Member State for many purposes and remained bound by EU law. The IP ended at 11 pm on 31 December 2020. On that date, a body of EU-derived rights and legislation, known as retained EU law (REUL), was converted into domestic UK law. On 1 January 2024, REUL that remained in force after the