Veset calculations: unsure when period began

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September 11, 2014

Question

I had thought that I wrote down the date⁄time when my last period began, but I just went to look and cannot find it –– so I do not know how to determine times for separation in my calendar. I have been calculating for irregular cycle –– yom hachodesh, haflagah, onah beinonit. I do have the dates for my previous three periods –– all in the night onah. I can remember the date of my hefsek and mikvah night but do not recall when my period began. Thanks.

Answer

There are different halachic approaches to this situation. We recommend that you try to reconstruct the day your period began, based on the usual interval from the start of your period to your hefsek taharah (e.g. five to seven days). Was there some event during those that you and your husband attended when you were or were not niddah? Does your husband have any recollection? Are you reasonably sure it was at night, as your other recent onot have been?

If one night of that range seems more likely, you should calculate your onot based on it. Otherwise, you should count backwards five days from your hefsek taharah (the day of the hefsek is day five and you're counting back to day one) and count that as your veset, since by then you were certainly in niddah.

Please write back with any further questions.