Bedika on Yom Hachodesh
Question
Hello, today we had a veset hachodesh. My wife forgot to do a bedikah and it’s after nightfall. Does she have to refrain from relations? Can she still do a bedikah?
Answer
Shalom!
Thank you for your question.
A woman who has a vest kavua must perform a bedika on the yom hachodesh. If it was omitted it must still be performed and relations are forbidden until it is performed.
A woman with a vest eino kavua (as is the case with most women) must perform a bedika on the yom hachodesh, but if it was omitted, a later bedika is not required, However, it is important to note that generally, vest be'inon'is falls with the veset hachodesh and with regard to veset beinon'is, one has to do a bedikah when immediately when one remembers. and relations are forbidden until it is performed.
Source
YD 184 with commentaries