In Benching, add Al Hanissim into the second beracha. In Shemoneh Esray, add Al Hanissim into Modim. This applies to all 8 days of Chanuka. (ShA 1)
The proper nusach is:
V’al hanissim – not Al hanissim
K’sh’omda malchus yovon – not k’sh’omda alayhem
l’hashkicham torasecha – not mitorasecha
shemonas yemay Chanuka ayloo l’hodos (MB 1,8)
We do not mention Chanuka or Purim in the Al Hamichya. (MB 2)
If you added Al Hanissim in the wrong place it is not considered a hefsek. (ShaH 2)
If you forgot to add Al Hanissim, whether in benching or tefilla, you do not repeat. (ShA 1 – MB 3)
If you remember your mistake in that same beracha, and you did not yet say “Hashem” of Baruch atta…, return to Al Hanissim and continue in order. (ShA 1)
If you forgot Al Hanissim, there is a compensatory tefilla which can be said on Chanuka and Purim. It goes: “Horachamon hu yaaseh lonu nissim v’niflaos k’shaym she’osissa la’avosaynu bayomim hohaym bazman hazeh. Bimay Mattisyohu…. / Bimay Mordechai…”. This should be inserted in benching at Horachaman.( On Rosh Chodesh, say the Horachaman for Rosh Chodesh first.) In tefilla, this Horachaman should be said after Shemoneh Esray before Yihyu l’ratzon. (Rama 1 – MB 4,5)
Al Hanissim must be added to Musaf Shemoneh Esray on Shabbos and Rosh Chodesh as well. (ShA 2)
