Just for the Poor, or Also for Mitzvos?
1. Maaser money was instituted for the poor and it is their money (מהרי"ל, רמ"א יו"ד סי' רמ"ט ס"א ). Some poskim say it must be given to the poor and may not be used for other mitzvos (שם ).
2. Others say one may use maaser money for a mitzva if the mitzva cannot be done without it (תשו' מהר"ם, מהרש"ל, דרישה, ט"ז סק"א, ש"ך סק"ג ). This is the general minhag (הגר"נ קרליץ באורח צדקה פי"א הע' ח').
3. Therefore, when one accepts upon himself to give maaser, he should l’chatchila stipulate that he should also be able to use it for mitzvos, satisfying all opinions (שו"ת חת"ס יו"ד סי' רל "א הובא בפתח"ת סי' רמ "ט סק"ב). Even if he gave to the poor three times without making this condition, he may still stipulate that from now on his maaser can also be used for mitzvos (שו"ת בצל החכמה ח"ד סי' קס "ג ), since his future maaser money does not yet exist and does not belong to the poor (שו"ת ערוגת הבשם יו"ד סי' ר "כ ).
4. Chiyuv. The poskim write that even according to the meikel opinion, one may only use maaser money for a voluntary mitzva, e.g., donating lights or other necessities to a shul, but it may not be used for chiyuvim, e.g., tefillin, mezuza, lulav and esrog, kiddush, shofar or the like (לבוש סי' רמ"ט ס"א, לקט יושר יו"ד עמ' 76).
5. Chomesh. One who gives a fifth to fulfill the mitzva in the best way (Issue 54, par. 9) may use half of it [a tenth] for mitzvos – even without prior stipulation, and even just for hiddur mitzva (שו"ת אג"מ יו"ד ח"ג צ "ג ) – and the other half for the poor (אהבת חסד ח"ב פי"ט ס"ג ).
