2,810. "Until Pesach" vs. "Through Pesach"
Hilchos Nedarim 10:7
If someone prohibits himself to benefit from something until Passover, he is only prohibited until the start of the holiday regardless of whether he said “until before Passover” or “until Passover.” If he says: “while it’s Passover,” then he’s prohibited until after Pesach. If he said: “until the wheat harvest,” “until the grape harvest,” “while it’s the grape harvest” or “while it’s the wheat harvest,” he is only prohibited until the specified time arrives.
Hilchos Nedarim 10:8
The general rule is that when there’s a designated time for something in a vow, a person is only prohibited until that time arrives. If the vow specified “while it’s X,” then one is prohibited until that time ends. If something doesn’t have a designated time, like the wheat harvest or the grape harvest, then one is only prohibited until that time arrives regardless of whether he said “until X” or “while it is X.”