§ 1. An action to execute a penalty is extinguished by prescription if the judge’s decree of execution mentioned in can. 1651 was not notified to the offender within the periods mentioned in can. 1362; these periods are to be reckoned from the day the condemnatory judgement became an adjudged matter. § 2. The same applies, with the necessary adjustments, if the penalty was imposed by an extra-judicial decree.
Source: Code of Canon Law (Vatican.va)