If you are active duty in any of the five branches of the armed forces or the National Oceanic and Atmospheric Administration (NOAA) you earn 30 days of leave (paid vacation) every year.

Earned Leave
Military and NOAA members earn 2.5 days of leave for each month of service. Up to 60 days of leave can be banked (accrued) over a two year period, but your leave balance is checked on the first day of the fiscal year (October 1) and any excess leave above 60 days is forfeit.

Special Note: Since the events of September 11, 2001 the Armed Forces have been authorized a special leave accrual that allows Servicemembers who would normally lose annual leave on October 1 to carry over as many as 90 days of leave into the next fiscal year if they were unable to take leave due to operational commitments. If you are among those affected by this change, you will have up to 30 days of excess leave to use until the end of FY2005.

Selling Back Accrued Leave
If have accrued leave to your credit at the time of your discharge or re-enlistment, you may be entitled to sell back leave. Leave is valued on the basis of the basic pay. Each day of leave is worth a single days basic pay.

However you can't receive payment for more than 60 days. Additionally you can't sell leave if you are discharged for the purpose of accepting a commission or a warrant in any uniformed service. You also cannot sell any leave you elect to have carried over to a new enlistment in any uniformed service on the day after the date of your discharge, but you can receive payment for any leave you elect not to carry over to a new enlistment.