If it is only coming from the K-1s, it is definitely concerning to me since there are no dollar figures on my K-1s for part III box 6 or for box 20 with a code of AC. I did see where code AC actually refers to REIT dividends which is helpful. Double checked the input and the number is not coming from there. All box 6 and Box 20 code AC are zero for my K-1s. Still a mystery.
