Halakhah su Levitico 27:31

That is that He commanded us to extract the second tithe. And that is His saying, "You shall surely set aside [a tithe of all the yield of your sowing that is brought from the field every year" (Deuteronomy 14:22). And the language of the Sifrei (Sifrei Devarim 105:1-2) is, "'You shall surely set aside' - teaches that the tithe is not to be taken from one year for another. This tells me only of the second tithe, of which Scripture speaks [here]. From where [do we know] to include other tithes? [Hence] we learn to say, 'You shall surely set aside.'" And the language of the Torah is that this tithe be brought up to Jerusalem and that its owners eat it there; and this was already [discussed] earlier (Sefer HaMitzvot, Positive Commandments 119). And Scripture already specified about this commandment, that if it is impossible for him to bring it - due to the far distance - he redeems it, brings up its money to the Chosen [Temple] and spends it there exclusively for food. And that is His saying, "should the place be too far from you, etc." (Deuteronomy 14:24). And the language of the Torah also already appeared about the law of this commandment - that if he redeemed it for himself, he adds a fifth. And that is His saying, "And if a man will at all redeem of his tithes, [he shall add to it the fifth part of it]" (Leviticus 27:31). And the regulations of this commandment have all already been explained in Tractate Masser Sheni. And it too is only an obligation with the produce of the Land of Israel by Torah law. And this tithe is only eaten in the presence of the Temple; and the language of the Sifrei (Sifrei Devarim 106:4) compares the eating of the firstborn animals to the second tithe, "Just as firstborn animals are eaten only in the presence of the Temple, so too is [the second] tithe eaten only in the presence of the Temple." (See Parashat Reeh; Mishneh Torah, Second Tithes and Fourth Year's Fruit 1.)

From the laws of the commandment is that which they, may their memory be blessed, said (Berakhot 35a) that one who wants to redeem the fourth year plant, redeems it like the second tithe, which [can be] redeemed - meaning to say, that he redeems it with money and brings [that] up to Jerusalem. And if he redeems it himself, he adds a fifth. As so is the law with the second tithe, from that which it is written about it (Leviticus 27:31), "And if a man surely redeems his tithes." But one who redeems the second tithe for others, does not add a fifth. And he does not redeem [the fourth year plant] until it reaches the season of the tithe; as it is stated about it (Leviticus 19:25), "to increase its produce for yourselves" - and they, may their memory be blessed, expounded (Sifra, Kedoshim, Section 3:10), "Until it becomes produce" - meaning to say that it reaches the season of the tithe, and that is a third of its ripeness. And according to Rambam (Mishneh Torah, Laws of Second Tithes and Fourth Year's Fruit 9:2), may his memory be blessed, we do not redeem it when it is attached [to the tree], like the tithe. But others explain (Rash on Orlah 5:5) that we redeem it even attached. And it is called money of the Higher Realm, like the tithe. And therefore it cannot be acquired as a gift - unless he gave it when it is still unripe fruit, as the obligation has not yet rested upon it, as we said. And its law in the other things - such as eating, drinking and anointment - is like the tithe. And on the commandment of the second tithe in Parshat Reeh Anochi (Sefer HaChinukh 473), we will write more about it at length with God's help.

The commandment of the second tithe: To remove the second tithe from the produce in four years of the sabbatical cycle, meaning to say, after we separate the first tithe that is given to the Levites, that we separate yet another tithe. And hence it is called the second tithe. And the law of this tithe is that it be eaten in Jerusalem. And about it is it stated (Deuteronomy 14:22), "You shall surely tithe the produce of your seed." And Scripture elucidates that if the place is far from us and we cannot carry it there except with great burden and much expense, that we can redeem it and bring up its value [to] Jerusalem and spend it there only for the needs of eating and drinking. And Scripture likewise elucidates that the one who redeems his tithe needs to add a fifth to the value - which is to say that if it was worth four dinar, that he eat instead of it [that which costs him] five dinar in Jerusalem. And about this is it stated (Leviticus 27:31), "And if a man surely redeems from his tithe, he shall add its fifth to it." And they, may their memory be blessed, made a precise inference (Kiddushin 24a): "'From his tithe - but not from the tithe of his fellow; 'a man from his tithe' - but not a woman."