I was just about to send the exact same question. Turbo tax program (using Premier) wants to categorize Code AG as Gross Receipts for section 448 (c), but the K1 indicates that the value reflects Gross receipts for Section 59A (e). No clear workaround using the forms as opposed to the step by step mode. Any clarification on this would be much appreciated. Thanks!
According to the IRS instructions for the K-1 Box 20, Code AG is for Gross receipts for section 448(c). Check back with the partnership that issued the K-1 for guidance on entering the number you have for Gross receipts for section 59A (e) in your tax return.
If you don't hear back from the issuer of the K-1, just leave it out of your return. Section 59A of the Internal Revenue Code deals with tax on base erosion payments of taxpayers with substantial gross receipts (large corporations/partnerships).