פירוש על קידושין 47:3

If the money and the tithe are her husband’s then all would agree that she is her husband’s agent and must add the fifth. And if it is her money (inherited), then all should agree that she is exempt from the tithe.
Therefore, the Talmud suggests that it must be a case where someone gives her money on condition that she use it to redeem the tithe. The rabbis hold that this money is automatically her husband’s and therefore, she is his agent and must add the fifth. R. Meir says it is not automatically her husband’s and therefore she need not add the fifth.
These opinions are opposite of those we saw above, and thus both seem to be contradictory.

Abaye says that we should reverse the opinions.
But, as usually happens, Rava finds a way not to reverse the opinions. The case is one of tithe which she inherits from her father’s estate. According to R. Meir, second tithe is holy, and therefore her husband does not acquire it. When she redeems the produce, she is redeeming her own tithe.
The other rabbis hold that second tithe is not holy. Her husband does acquire it (or at least certain rights) and therefore when she redeems it, she is fulfilling her husband’s agency. She must add the extra fifth.