As clarified, the generous [but not required] amount to give for tzedakah is a fifth of one’s earnings, not only a tenth (ma’aser). However, some authorities say that in certain situations one is obligated to separate a fifth of his earnings, as in when the person knows that there are widows or orphans, or even ordinary poor people, who are hungry for food or who need clothing and they have no means of helping themselves. In such situations, every person is duty-bound, and it is the basic halacha, to separate a fifth to tzedakah. This is also the opinion of the Gaon of Vilna. However, even according to this opinion, it is only when the person giving can afford to distribute a fifth to tzedakah, but otherwise he is not obligated to overexert himself to do this, though it would be a mitzvah to do so.
ט׳ באב ה׳תש״פ
Hashem says to you what is the best and what he demand from you, just do good deeds and Ahavas Chessed and meekness with Elokecha (Micha 6,8) 1