I have one onos halflaga which is 45 days. It always comes out that I already get my next veset when this onos haflaga comes out carrying over from the previous veset. What is the halacha? If you get a new veset, do onos perisha days of the previous veset automatically cancel or do you still have to keep it?
The onas haflaga is cancelled after 3 consecutive periods that came before day 45. I.e. if you get to day 45 (without getting a period) in the first 3 cycles since the 45 day haflaga, then day 45 is considered a veset. However, if the first three periods came before day 45, then the ’45 day onas haflaga’ is cancelled in subsequent cycles.
All the best
There is a dispute between the Rema (189:130) ,the Taz (ibid) and the Shach (ibid) if a long haflaga (e.g. 45 days) is cancelled out by a short haflaga (e.g. 40 days). Rav Shlomo Zalman Auerbach’s conclusion regarding this dispute was as answered above.