There are million ways to do this. but here is what worked for me. You will need your date of birth variable to have month, day and year.
COMPUTE age_year = (DATE.MDY(11,01,2010) - BirthDate) / (60*60*24*365.25) .
FORMATS age (F3.0).
NOTE: This will create an AGE variable, as of now, not the age of respondent at the time of survey. To do that you would need survey date.