I just had the same thing happen to a client. I'm using Lacerte. My problem is I cannot reproduce the number now? And there's no worksheet! I can't explain how the amount was determined. My total federal depreciation was $20,169 (80% bonus depreciation on $24,989 total cost plus $178 current depreciation) and the subtraction on the OK return is $4,820. I'm sitting here beating my head against the desk. I read that you have to add back 80% of the federal Depreciation and then you are allowed a subtraction for 1/4 of that for the next 4 years.