3,011. The Extra Fifth

Hilchos Arachin Vacharamin 7:3

The extra fifth doesn’t preclude redeeming consecrated property; once the principal has been paid, the item is rendered secular and one is permitted to benefit from it under Biblical law. By rabbinic enactment, one may not benefit from the item until the extra fifth has been paid, out of concern that one might end up forgetting to pay it. Regardless, the Sages permitted one to use a redeemed object on Shabbos even if the extra fifth wasn’t paid so as not to impede one’s enjoyment of Shabbos, plus we assume that the Temple treasurers will collect payment from him.

Hilchos Arachin Vacharamin 7:4

Regarding an animal that was consecrated for the altar but which became blemished, if the one who consecrated it redeems it, he must add the extra fifth just as with other consecrated things. The one who consecrated it must add a fifth, not one who receives atonement through the offering after the blemished animal is redeemed. One must add a fifth when redeeming the item that was originally consecrated, but not when redeeming something that was consecrated when redeeming the original item (as will be explained in the next halacha). This is derived from Leviticus 27:15: “If the one who consecrated redeems his house, he must add a fifth.” “One who consecrated” must add a fifth, not one who extends the consecration.