48 CFR §2432.703-1

1. (b)
   1. (1)Except as described herein, a fixed-price contract may be funded incrementally only if—
      1. (i)Sufficient funds are not available to the Department at the time of contract award or exercise of option to fully fund the contract or option; and
      2. (ii)The contract (excluding any options) or any exercised option—
         1. (A)Is for severable services; and
         2. (B)Does not exceed one year in length; and
         3. (C)Is incrementally funded using funds available (unexpired) as of the date the funds are obligated; and
      3. (iii)If applicable, the contract uses funds available from multiple (2 or more) fiscal years and Congress has otherwise authorized incremental funding.
   2. (2)An incrementally funded fixed-price contract shall be fully funded as soon as funds are available.