CT-399: Depreciation Adjustment Schedule (2025)
New York · NY DTF · Used for tax years 2025
Form CT-399 is New York’s Depreciation Adjustment Schedule for corporations. It reports federal and New York State depreciation, adjustments for disposed property, and the resulting modifications to New York State taxable income.
Who files this form
Form CT-399 is a depreciation adjustment schedule for corporations under New York Tax Law Articles 9-A and 33. It covers depreciable property that requires or is entitled to a depreciation modification when computing New York State taxable income.
The schedule includes sections for ACRS/MACRS property and property qualified for federal special depreciation under IRC section 168(k)(2).
What you'll need
Have the following information available to complete the schedule:
- The corporation’s legal name and employer identification number.
- Each property item’s description, date placed in service, and cost or other basis.
- Accumulated federal depreciation and the federal depreciation deduction.
- The New York State depreciation method, life or rate, accumulated depreciation, and allowable depreciation.
- For disposition adjustments, total federal and New York State depreciation taken in prior and current years.
- Whether you disposed of property during this tax period for which an investment tax credit was previously claimed.
Common mistakes
- Do not list all depreciable property automatically. Part 1 says to list only property that requires or is entitled to a New York State depreciation modification.
- If you need extra sheets, use the same format as the corresponding section of the form.
- If you disposed of property that was listed on this form in a prior year, complete Parts 2 and 3.
- In Part 2, put the difference in column E when federal depreciation is larger, or in column F when New York State depreciation is larger.
- Mark Yes or No to answer whether you disposed of property during this tax period for which an investment tax credit was previously claimed.
Questions people ask
Where do I list property that qualifies for federal special depreciation?
Use Part 1, Section B for property qualified under IRC section 168(k)(2) for federal special depreciation.
What if I need more space to list property?
You may attach separate sheets for Part 1, Sections A and B, and Part 2. Format the information the same way as the corresponding section and enter the amounts from the attached list where indicated.
How do I calculate a disposition adjustment?
For each item in Part 2, compare total federal depreciation, including the applicable federal special depreciation deduction, with total New York State depreciation used in prior and current years. If federal depreciation is larger, subtract New York State depreciation and enter the difference in column E. If New York State depreciation is larger, subtract federal depreciation and enter the difference in column F.
Where do New York S corporations report the Part 3 totals?
For filers of Form CT-3-S, the form directs you to enter the amount from line 10, column A, on Form CT-34-SH, line 2, and the amount from line 10, column B, on Form CT-34-SH, line 4.