Responsa for Bava Metzia 146:7

Q. A and B jointly loaned money to a Gentile. When the Gentile repaid part of his obligation, A wanted to keep the entire sum for himself, and told B to collect his part from the Gentile.
A. A loan in the hands of a Gentile is very insecure. Therefore, A cannot dissolve the partnership until the entire loan is collected; and B is entitled to his share of the money already paid by the Gentile.
This Responsum is addressed to R. Isaac.
SOURCES: Cr. 49; Pr. 916; L. 372; Mord. B. M. 392; Rashba I, 869; Mordecai Hagadol, p. 293d.

Q. A claims that his assets, equal to forty marks, for which the community demands a tax, are not taxable.
A. The decisions on questions of taxation are dependent more on custom than on talmudic law. The following rule is generally accepted by the communities: In any tax dispute between an individual and the community, the latter first collects the tax and then goes to court. Therefore, even before the tax is collected, the community is considered to be in possession of the tax-money, and the burden of proof falls upon the individual. This is not only an accepted custom, but also good talmudic law, and is operative even in a new community where there are no established customs. But if the community in question has a different custom, that custom prevails, though it be at variance with talmudic law.
This Responsum is addressed to R. Eliakim ha-Kohen.
SOURCES: Pr. 106; Mord. B. B. 522; cf. also Cr. 49; Pr. 708, 915; L. 371; Am II, 130. Agudah B.M. 108; Moses Minz, Responsa 72; Terumat Hadeshen 341.

Q. A and B, former residents of T, escaped from the prison (where the other Jews of T were held), but their investments have remained in the hands of residents of T. Are A and B obliged to participate in the payment of the ransom money levied on the Jews of T?
A. If the Jews of T were accustomed to be partners in the payment of exorbitant taxes, A and B must pay their share of the aforementioned tax. The obligation to pay that tax was created at the time they were all cast into prison, and after that A and B could no longer free themselves from such obligation.
SOURCES: Am II, 130.

The custom is well established throughout the kingdom that when an individual has a complaint against the community regarding the tax he was assessed with, he must first pay that tax and, then, may summon the community to court, for the community prefers to be in possession of such tax-money. As corroborative evidence of the legality of this procedure I cite the talmudic ruling that those who pay the capitation tax for others are justified in forcing the latter in their service (B. M. 73b), since "the law of the land prevails". Moreover, since the members of the community are partners in the payment of the taxes, no individual may willfully withdraw from the partnership. Since the majority (of the members of a community) may force the minority to abide by its rulings (B. B. 8b), it may certainly force an individual to pay his taxes. The burden of proof to the contrary rests upon the person who seeks to deviate from this rule.
Since the overlord customarily collects his taxes collectively from the entire community, the exact obligation of each member of the community regarding such tax becomes determined as if already collected (the very moment the overlord demands the collective tax); and if the overlord subsequently desires to free or relieve one member at the expense of the others, he has no right to do so. Such an act on his part is not considered "law of the land," but rather constitutes outright robbery, and is, therefore, not valid.
SOURCES: Cr. 49; Pr. 708, 915; L. 371; Am II, 130. Cf. Agudah B. M. 108; Weil, Responsa 124; ibid. 133; ibid. 147; Menahem of Merseburg, Nimmukim (36); Terumat Hadeshen 341.

The custom is well established throughout the kingdom that when an individual has a complaint against the community regarding the tax he was assessed with, he must first pay that tax and, then, may summon the community to court, for the community prefers to be in possession of such tax-money. As corroborative evidence of the legality of this procedure I cite the talmudic ruling that those who pay the capitation tax for others are justified in forcing the latter in their service (B. M. 73b), since "the law of the land prevails". Moreover, since the members of the community are partners in the payment of the taxes, no individual may willfully withdraw from the partnership. Since the majority (of the members of a community) may force the minority to abide by its rulings (B. B. 8b), it may certainly force an individual to pay his taxes. The burden of proof to the contrary rests upon the person who seeks to deviate from this rule.
Since the overlord customarily collects his taxes collectively from the entire community, the exact obligation of each member of the community regarding such tax becomes determined as if already collected (the very moment the overlord demands the collective tax); and if the overlord subsequently desires to free or relieve one member at the expense of the others, he has no right to do so. Such an act on his part is not considered "law of the land," but rather constitutes outright robbery, and is, therefore, not valid.
SOURCES: Cr. 49; Pr. 708, 915; L. 371; Am II, 130. Cf. Agudah B. M. 108; Weil, Responsa 124; ibid. 133; ibid. 147; Menahem of Merseburg, Nimmukim (36); Terumat Hadeshen 341.

Q. The leaders of the community demanded that the tutors and scribes who do business in their town, with their own money or with that belonging to others in their hands, pay taxes from such moneys. The scribes and tutors refused to pay the taxes and summoned the leaders to court. The latter refused to appear, claiming that according to the regulations of the community, anyone who is asked to pay a tax must do so, otherwise the community leaders have a right to pawn his property. They see no reason, therefore, why they should answer a summons to court.
A. The scribes and tutors must first pay the levied tax; for the community is considered to be in possession of the tax money and the burden of proof lies on the individual. But, if the scribes and tutors later summon the leaders of the community to court, the latter must appear and present their claims before that body; for a community is not outside the pale of justice any more than an individual.
SOURCES: Pr. 716.

The custom is well established throughout the kingdom that when an individual has a complaint against the community regarding the tax he was assessed with, he must first pay that tax and, then, may summon the community to court, for the community prefers to be in possession of such tax-money. As corroborative evidence of the legality of this procedure I cite the talmudic ruling that those who pay the capitation tax for others are justified in forcing the latter in their service (B. M. 73b), since "the law of the land prevails". Moreover, since the members of the community are partners in the payment of the taxes, no individual may willfully withdraw from the partnership. Since the majority (of the members of a community) may force the minority to abide by its rulings (B. B. 8b), it may certainly force an individual to pay his taxes. The burden of proof to the contrary rests upon the person who seeks to deviate from this rule.
Since the overlord customarily collects his taxes collectively from the entire community, the exact obligation of each member of the community regarding such tax becomes determined as if already collected (the very moment the overlord demands the collective tax); and if the overlord subsequently desires to free or relieve one member at the expense of the others, he has no right to do so. Such an act on his part is not considered "law of the land," but rather constitutes outright robbery, and is, therefore, not valid.
SOURCES: Cr. 49; Pr. 708, 915; L. 371; Am II, 130. Cf. Agudah B. M. 108; Weil, Responsa 124; ibid. 133; ibid. 147; Menahem of Merseburg, Nimmukim (36); Terumat Hadeshen 341.