Level 15

Someone else puzzled over this earlier, but I can't find the post. Look at the k-1 instructions:

Code AC. Gross receipts for section 448(c) Use the gross receipts
amount to figure the business interest
expense you can deduct, if
applicable. See section 163(j) and the
Instructions for Form 8990 for details.

It may be the program is not yet read for prime time.