Screen 28, way down at the bottom:

Section 383/384 Limitation

Enter any limitation on the amount of the general business credit that can be applied due to ownership change. Or, enter the limitation on the use of pre-acquisition excess credits of one corporation to offset the tax attributable to recognized built-in gains of another corporation. Attach a computation of the allowable general business credit. Use the next field, “IRC section for limitation: 1=383 (default), 2=384” (Screen 28.1, code 499) as necessary to designate the appropriate verbiage to print, such as “Sec 383” or “Sec 384.”