You are obligated in the reading of the Megillah, in Matanot L’Evyonim, and in the Mitzvah of the festive meal (Seudah) and joy.

Regarding Mishloach Manot, there is a dispute:

• The Pri Chadash (Siman 695) requires it only on the 14th, as that is the primary day of Purim for most of the world.

• The Pri Megadim (ibid.) requires it on both days.

• This is also the ruling of Maran the Ben Ish Chai (Parshat Tetzaveh), and it was the custom of the Holy Ari, zatzal (see Kaf HaChaim ibid.).

Regarding “Al HaNissim” in the Amidah prayer and Birchat HaMazon: It should be recited on the 15th out of doubt (Mishna Berurah 693:6).

However, on the night of the 15th, “Ve’Atah Kadosh” is not recited, and a Sefer Torah is not taken out on the day of the 15th (Kaf HaChaim). In contrast, according to Maran the Ben Ish Chai, the Torah should be taken out and read, but without reciting the blessings over the Torah reading.