Finding someone's date of birth might be a bit of a challenge if you don't have much information to go on. Many first and last names are quite common, and if you don't have both of those to start off your search, the resulting possibilities might leave you feeling like you're digging for a needle in a haystack. But if you have a Social Security number, finding out the corresponding date of birth for the number's owner should be a straightforward process.
Search for information in the online Social Security Death Index at Ancestry.com (see Resources). Provide any combination of first name, last name and Social Security number. Use the advanced search options to specify year of birth, year of death or last residence.
Contact Social Security directly with form SSA-711: Request for Deceased Individual's Social Security Record (see Resources). Social Security charges $27 for this service.
Search public records such as voter registration cards, birth and marriage certificates, divorce decrees, vehicle accident reports and professional license records. You may often search these by Social Security number. Records like these are considered public records, and are usually available in vital statistics offices and other government-run offices on a city, county and state-wide level.