Can one use maaser money for a yisachar zevulun shutfis, even to the extent of drawing up a formal contract?
A Yisachar Zevulun shutfus is business deal between the two people, that one person will learn and the other person will work. This is why it is not a tenth of one’s money but half of it, even though a person may not give more than 20% of his earnings to tzedakah. This is why a Yissachar Zevulan deal has a contract, but tzedakah doesn’t. Additionally the Yissachar Zevulan deal is not brought in Hilchos Tzedakah but rather in Hilchos Talmud Torah (Y:D 246-1). Therefore one can not use maaser money for a Yisachar Zevulan deal.
Igros Moshe Y:D 4-37, Borach Tzedakah pg. 366 in the name of R’ N. Karelitz shlit”a.