Priority/Cut Off Dates
The priority date decides a person's turn to apply for an immigrant visa. If you are being petitioned by a family member, your priority date is the date when the petition was filed at the U.S. Citizenship and Immigration Services office or submitted to an Embassy. Under U.S. law, there are numerical limits on the number of immigrant visas that can be granted to nationals from any one foreign country. The limit is based on place of birth, not citizenship. Because of the numerical limits, there may be a waiting time before you are eligible to be interviewed. If your priority date is before than the cut-off date listed on the monthly Visa Bulletin, your case is current and can now be processed. However, if your priority date comes after the cut-off date, you will need to wait until your priority date is reached (becomes current).
To find out whether a preference case is current, see the Visa Bulletin.