No, you don't need to complete your cost segregation study before December 31st.

The critical deadline is your tax filing deadline, not the calendar year-end.

As long as the study is completed before you file your tax return for the year you want to claim the benefits, you can take full advantage of the accelerated depreciation.

For example, if you placed a property in service in 2024, you can conduct the study anytime in 2025, as long as it's completed before your 2024 tax return filing deadline.

April 15th for individuals (or October 15th with extension), or March 15th for partnerships and S-Corps (September 15th with extension).

The study will analyze your property as of its placed-in-service date and provide depreciation schedules starting from that date.

If you've already filed your tax return without a cost segregation study, you still have options.

You can file an amended return for that year if you haven't yet filed the following year's return.

Otherwise, you'll need to file Form 3115 (Application for Change in Accounting Method) to adjust your depreciation going forward and capture the "catch-up" depreciation you missed.

The flexibility in timing allows you to complete renovations, gather documentation, and work around your schedule without rushing to meet a year-end deadline.

This also means you can strategically time the study based on your tax planning needs and cash flow considerations, making it a more manageable process that fits your business timeline rather than being forced by an arbitrary calendar deadline.