CRA requires an explanation for a large amount reported on my 2023 Turbotax return for "Line 25600 additional deductions"  I find that part of this comprises 15% exempt portion of U.S. Social Security, which seems correct.  However I cannot find any other item to support the remaining amount except for Line 11400 CPP Benefits (Box 20 0f T4 (P) slips) for the exact same amount.

Has Turbotax included CPP benefits incorrectly in Line 25600, or is there another item that I cannot find to explain the item?

Thank you.