Can you sacrifice a creature to a sorcery-speed sacrifice outlet during your opponent's turn?

Sorcery-speed activated abilities are restricted by the same timing rules as casting a sorcery spell. Under CR 307.1, sorceries can only be cast during your own main phase when the stack is empty. An activated ability with 'activate only as a sorcery' (or equivalent wording) follows the same restriction per CR 702.2c and CR 117.1.

During your opponent's turn, you generally only have priority to activate instant-speed abilities. A sorcery-speed sacrifice outlet — such as Ashnod's Altar does NOT have (it's instant speed), but something like Nantuko Husk's ability used at sorcery speed would — cannot be activated when it isn't your turn, because the timing permission is simply not granted.

It's worth noting that many popular sacrifice outlets (Ashnod's Altar, Viscera Seer, Altar of Dementia) are actually instant-speed and CAN be activated on your opponent's turn. Always check whether the outlet says 'activate only as a sorcery' or has no timing restriction.

Example: It's your opponent's combat step and they attack you. You control a creature and a sorcery-speed sacrifice outlet. You cannot sacrifice the creature to the outlet to trigger a death effect right now — you would need to wait until your own next main phase with the stack empty.

Relevant rules: CR 307.1 (sorcery timing), CR 117.1 (timing of activated abilities), CR 117.2 (abilities that follow sorcery timing).