Rosh Chodesh and Missed Prayers

If a person unavoidably missed reciting one of the daily prayers through no fault of his own, halachah  requires that they make it up at the next prayer. This means first reciting the regular Amidah for the current time, and then repeating that Amidah as tashlumim (makeup).

If someone mistakenly switched the order — saying the tashlumim first and then the current prayer — they do not fulfill their obligation and must repeat both in the correct order.

Based on this, someone who missed Minchah on Erev Rosh Chodesh must recite Maariv of Rosh Chodesh twice, including Ya’aleh VeYavo in both recitations.

• If they forgot Ya’aleh VeYavo in both, or included it in the first but not in the second, they have still fulfilled their obligation.

• If they included it in the second but not in the first, they technically fulfill the requirement. However, it is recommended that they repeat the Amidah as a nedavah (voluntary prayer), with this condition:

"If I am required to repeat it, let this be for tashlumim; if not, let it be a nedavah."

However, if they specifically intended the first recitation for Maariv and the second for tashlumim, then they do not need to repeat anything — even as a nedavah.
 

Missed Maariv on Rosh Chodesh

If someone was unable to pray Maariv on Rosh Chodesh, they must recite Shacharit twice the next morning:

• The first Amidah for Shacharit.

• The second as tashlumim for Maariv.

If they forgot Ya’aleh VeYavo in the second Amidah, they still fulfill their obligation.

Although someone who forgets Ya’aleh VeYavo in Shacharit must normally repeat it, in this case the second Amidah is technically in place of Maariv, where Ya’aleh VeYavo is not required. Therefore, one does not have to repeat it.

If someone forgot Maariv on Rosh Chodesh, needs to pray Shacharit twice, but only remembers after they have already prayed Mussaf, they should now pray an additional Amidah for tashlumim for Maariv, adding a condition of nedavah:

"If I am required to repeat it, let it be for tashlumim; if not, let it be a nedavah."
 

Missed Shacharit on Rosh Chodesh

If someone was unable to pray Shacharit on Rosh Chodesh and it is now time for Minchah, they will need to pray three Amidah prayers in the following order:

1. Minchah (the regular prayer for now).

2. Mussaf (still within its proper time).

3. Tashlumim for Shacharit.

The order prioritizes Minchah over Mussaf, even though both are timely, because Minchah is tadir (a daily obligation), and "tadir kodem"—the more frequent mitzvah takes precedence.
 

Missed Minchah on the First Day of Rosh Chodesh

If someone missed Minchah on the first day of Rosh Chodesh—or recited Minchah but forgot Ya’aleh VeYavo and only remembered after nightfall—they must pray Maariv twice on Rosh Chodesh:

• The first Amidah for Maariv itself.

• The second as tashlumim for Minchah.

If they forgot Ya’aleh VeYavo in the second Amidah, they still fulfill their obligation.

Although Ya’aleh VeYavo is required in Minchah on Rosh Chodesh (and one repeats if they forget it), the tashlumim Amidah cannot be stricter than the Maariv for which it is being said, where Ya’aleh VeYavo is not required.

Remembering Only After Rosh Chodesh Ends

If someone forgot Minchah on Rosh Chodesh entirely and only remembers after Rosh Chodesh ends—once nightfall has begun (tzeit hakochavim)—they must pray Maariv twice on that night (the night following Rosh Chodesh):

• The first Amidah for Maariv of the weekday
• The second as tashlumim for the missed Minchah.