Tractate Meilah - Chapter 3 - Mishnah 1 מעילה פרק ג׳ משנה א׳

The offspring of a hatat, the substitute of a hatat, and a hatat whose owner has died, are left to die. A hatat whose year has passed or which was lost and found blemished: If the owners obtained atonement [afterwards, through another animal], is left to die, and it does not make a substitute; it is forbidden to derive benefit from it, but the law of sacrilege does not apply. If the owners have not yet obtained atonement, it must go to pasture until it becomes unfit for sacrifice. It is then sold and another is bought with the money. It makes a substitute, and the law of sacrilege does apply.