On Amud Aleph R. Yehuda says that the shekalim are "olin lahem lshanah habaah" (Rashi is mashmah that they don't have to be shokel again the next year.) Yet on Amud Beis it says that an animal from this year can't be used the next year because of "Olas Chodesh BChodsho." If the shekalim themselves can come from last year, and I assume that means one can buy next year's animals with them, then why can't the animal itself be transfered from one year to the next?
Yaakov Siegel, Miami, Florida
A number of Rishonim ask your question (among them the Tosfos ha'Rosh). However, I will cite just the answer of R. Simchah mi'Desvi, who cites the question in the name of the Tosfos Yeshanim, which I did not find), and whose answer I find the clearest.
Remember that what the Torah requires is to use animals that have been purchased from the new Terumah, as the Gemara specifically states. Consequently, the Gemara disqualifies any animal that was purchased with a Terumah that was effected last year with last year's money (according to the current contention). It does not disqualify an animal that is purchased with a Terumah that was effected this year with last year's money, because it falls under the category of a new Terumah.
Another answer that occurred to me is based on the fact that, whereas an animal that is leftover from last year is Kodshei Mizbe'ach, leftover money is Kodshei Bedek ha'Bayis (which is not subject to most Pesulim that Kodshei Mizbe'ach are). Consequently, even though we currently think that last year's animal is Pasul even Bedi'eved, we would never think that with regard to leftover money.
Wishing you and yours a Kesivah va'Chasimah Tovah,
Eliezer Chrysler