My understanding is the 512-S Add-back for Duplicated Federal Depreciation is for tax years after Jan 1, 2023 if a taxpayer elects to immediately and fully expense qualified property for Oklahoma, they must add back federal depreciation that duplicates this treatment. In my situation, I have property setup for 27.5 SL depreciation that was placed in service in 2011 (100% business use). The 2025 depreciation was moved to the State return Part 2 line 15 (Depreciation) correctly, but was also placed on line 6 (Add-back duplicated federal depreciation) which cancels the deduction resulting in the Ordinary Income (loss) differing between the Fed and State Returns by the asset's depreciation amount for 2025.
