Veses HaChodesh: Keeping the Same Hebrew Date Next Month

5 min read · October 22, 2026

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The veses hachodesh is the anticipation that a period will come on the same Hebrew date as the last one began. It follows the Hebrew month, which is why a Gregorian period app cannot work it out.

Same date, same onah

A period that began on the day of 12 Shevat sets a veses hachodesh on the day of 12 Adar. Only that one onah is kept — not the whole day — unless your custom is otherwise.

When next month has no 30th

Hebrew months have 29 or 30 days. A period that began on the 30th has no matching date in a 29-day month. Customs differ: keep the 1st of the following month, keep the 29th, or keep nothing that month and the 30th the month after. A calendar should ask which you follow.

Becoming fixed

Three periods on the same Hebrew date in three consecutive months make a veses hachodesh kavua — a fixed veses. It is then anticipated every month on that date even if a period comes elsewhere in between, and it is uprooted only by three months without a period on it — a question to settle with your rav.

A flow that was already running

If a period began the day before the veses hachodesh and was still flowing in its onah, many hold the veses was not uprooted: she saw on it, and keeps it again next month alongside the new date.

This guide explains the general rules and the common customs. Where poskim differ it says so — it does not rule. For your own questions, ask your rav.