Bava Kamma 7B

אפילו פורתא נמי לא ליספו ליה!

The Talmud asks: But if that is the case, we should not provide him with even a slight amount of poor man’s tithe. Since his assets, based on their market value, have a high value, he is not to be classified as a poor person.

ואמר מר עלה: לא צריכא; דביומי ניסן יקרא ארעתא, וביומי תשרי זל ארעתא;

And the Master, Rabba, said concerning this: No, the halakha that he is provided with only up to half the value of his assets is necessary in a case where he cannot sell due to seasonal fluctuations in price. This is because in the days of the month of Nisan, which is the beginning of the harvest season, the market value of land appreciates, and in the days of the month of Tishrei, a time when the harvest had already been reaped and it is too late to prepare the land for the coming year, the market value of land depreciates.

דכולי עלמא ⁠– נטרי עד ניסן, ומזבני; והאי, הואיל ואצטריכא ליה זוזי ⁠– זבין כדהשתא. עד פלגא ⁠– אורחיה למיזל, טפי ⁠– לאו אורחיה למיזל.

Consequently, everyone generally waits until Nisan and sells only at that point. But this person, since he is in need of money, sells his land in Tishrei according to the current, lower, market price. Accordingly, based on the current market prices, his assets have a low value and there is justification in regarding him as a poor person. Yet, since if he waited until Nisan, as everyone else does, his land would have a high value, he cannot truly be classified as a poor person. Therefore, he is permitted to take only as much poor man’s tithe as will cover his losses. The Talmud explains why he is permitted to take only up to half the value of his land: Since it is the nature of land to depreciate up to half its value, and it is not its nature to depreciate more than that, he is entitled to take poor man’s tithe that is worth up to half the value of his land and the rest he can supplement by selling his land at its current, lower price.