«Вычитание» и сальдирование в гражданском праве

The article shows that «deduction» (including deductio/Anrechnung) is neither an autonomous legal institution nor a mode of extinguishing obligations, but an accounting technique for determining the amount of a claim that is already grounded in law. The error lies in attributing independent legal significance to arithmetic, thereby replacing the analysis of the juridical facts that created the need for calculation. Roman materials (deductio servitutis; remission of rent–remissio mercedis; the deduction vis-à-vis the bonorum emptor; the peculium) demonstrate that there is no single, unified «deductio»: the meaning of any deduction is always supplied by the surrounding doctrinal institution. German Anrechnung and the evolution of the Saldotheorie confirm that, where the performances are homogeneous, a single claim arises, and «deduction» plays only an auxiliary computational role. The so-called «compensazione impropria» in Italian law is not identical to Anrechnung: it partially overlaps in effect in certain situations but remains an indeterminate label aggregating heterogeneous constructs. The same problem afflicts the Russian notion of «saldo-netting». For Russian law, a narrow legal meaning of «saldo» is proposed: (1) the parties have exchanged performances; (2) where those performances are not equivalent, a single monetary claim arises for one party for the first time. Where counter-monetary claims already exist, only «set-off» applies, not «saldo-netting». A mere statement of a «saldo» in any broader sense uses the term in its accounting meaning; in that case, the legal regime must depend on the specific juridical fact underlying the «saldo». Ignoring this logic and substituting qualification with a reference to «saldo» leads to errors in dispute resolution. Keywords: deductio; Anrechnung; compensazione impropria; deduction; saldo; set-off; unjust enrichment; synallagma.