Establishing a business partnership with a non-Jew poses several complex Halachic issues. One might think that having a non-Jewish partner solves the problem of opening a business on Shabbat. However, on the contrary, it can create more problems than the other permitted arrangements. For example, if one contracts a non-Jew to perform a task on a per-job basis, the employee is not considered the agent of the Jew. The Jew did not require that the employee work on Shabbat, and if he chooses to do so, the Jew does not receive any benefit.
This is not the case with regard to partnership. If, for example, a Jew is a fifty-fifty working partner with a non-Jew, both parties are obligated to operate the business. The partners are likely to agree to an exchange of shifts, in which the non-Jew would work on Shabbat instead of the Jew, in return for the Jew working on another day instead of the non-Jew. Such an arrangement is prohibited because, essentially, the Jew has deemed the non-Jew his agent to run the business on Shabbat in his stead.
The Shulhan Aruch (Siman 245) rules that the easiest way to solve this problem is by signing a written, legally binding contract before establishing the partnership. The contract would stipulate that all profit earned on Shabbat belongs to the non-Jew and all the profit earned on another specific day of the week belongs to the Jew. The rest of the week they are equal partners. Accordingly, when the partnership was established, Shabbat was never a factor, since, essentially, the business does not belong to the Jew on Shabbat.
If the partners did not create such an arrangement, the profit earned on Shabbat is forbidden to the Jew. This is the Halacha even if the partnership was not fifty-fifty.
SUMMARY
It is permitted to make a legally-binding condition with a non-Jew, before establishing a business partnership, to give him the profit of Shabbat in return for the profit of a different day.
If such an arrangement was not made before establishing the partnership, the Jew is prohibited from benefiting from the profit off Shabbat.
