Two Passover

The 

First Passover (Pesach) is the primary seven-day Jewish festival held on 14–21 Nisan to commemorate the Exodus, while the Second Passover (Pesach Sheni) is a one-day "make-up" holiday on 14 Iyar—exactly one month later—for those who were ritually impure or traveling and missed the initial observance. 

Key Differences and Details:

• First Passover (14-21 Nisan): A major biblical festival involving strict prohibition of leaven (chametz) and the Seder meal. In 2026, this begins at sunset on April 1st and ends on April 9th Wikipedia.
• Second Passover (14 Iyar): Established in Numbers 9:6-14, this was a special concession for people who could not bring the Passover offering in the first month. It is considered a day of second chances and spiritual reflection.
• Observance: On Second Passover, matzo (unleavened bread) is eaten, but unlike the first, leaven may still be present in the home. It lasts only one day. 

Origins:
According to the Book of Numbers, during the second year after leaving Egypt, men who were unclean due to contact with a dead body requested to participate in the Passover sacrifice. God instructed Moses that those who were "tamei" (impure) or on a long journey could instead observe the Passover one month later. 

The two Passovers, 14 Nissan and 14 Iyar, exist because Pesach Sheni (Second Passover) on 14 Iyar acts as a "make-up" date for those who could not offer the Paschal lamb on 14 Nissan due to impurity, travel, or other circumstances. It represents a second chance for missed spiritual opportunities. 

• 14 Nissan (First Passover): The original date for sacrificing the Korban Pesach (Passover lamb) in the Temple, leading into the first night of Passover on 15 Nissan.
• 14 Iyar (Second Passover/Pesach Sheni): Occurs exactly one month later. It was established when individuals unable to partake in the first, due to being spiritually defiled or far away, requested an opportunity to bring the offering.
• Significance: It teaches that "it is never too late" to rectify spiritual shortcomings, even if the missed opportunity was due to negligence.
• Modern Observance: Although the Temple sacrifice cannot be performed, it is customary to eat matzah on 14 Iyar. 

While the main Passover is 15-21/22 Nissan, the 14th day of the first month (Nissan) is specifically the preparation day for the sacrifice.