Donation after Aliya

If you receive an aliya to the Torah on Shabbat and Jewish festival mornings, it is customary give a donation to the synagogue, but you are not required to do so by halacha (and you may not give the donation ON Shabbat!).
Note A synagogue may request a donation on Shabbat or Jewish festivals from someone who has received an aliya on Shabbat and may give that person a card to mail in after Shabbat has ended.
Note There is no expectation of giving a donation for aliyot on weekdays or at mincha on Shabbat.