Tithes must be given yearly – they cannot be paid in advance and one is not allowed to fall in arrears, and pay them back next year. This is learned from the repetition of the word “tithe” in the verse Tithe, you shall tithe, all the yield of your seed that comes out in the field year after year (Devarim 14:22), each year has its own tithe that must be given on time. When it comes to doing good, we cannot rest on past deeds or keep promising ourselves that tomorrow we will improve. Now is the time to act.