Can one use maaser money to fulfill a chumra. For example, if one lives in israel, can one use maaser money to pay the expense of a generator on shabbos so as not to use the general electricity which could be chilul Shabbos.
Maaser money may not be used for such a purpose. The intention of maaser money is to give it to charity (or, first and foremost, for the support of Torah), and although poskim permit donating it for other purposes, one cannot use it for the personal fulfillment of mitzvos, even when the mitzvah is not a full obligation.
Sources: See Darkei Moshe, Yoreh De’ah 249:1, who states that maaser cannot be used for candles in shul, because it belongs to the poor. Although poskim permit making donations to other causes, these causes are limited to matters on which there is no previous obligation. See Chasam Sofer 232; Taz 249:1. Yet, this does not mean that maaser can be used even for personal matters for which there is (or might be) no obligation, such as the generator, which can be considered a chumra. Rather, the money must be donated for a charitable cause.