Can a roof replacement in a rental be a "qualified property" for the special depreciation allowance?

You are correct... a roof is a structural component of a building. The IRS mandates that a new roof be depreciated over 27.5 years using the straight-line method.

Bonus Depreciation does not apply to assets with a recovery period longer than 20 years; Thus, your residential roof replacement does not qualify for the 100% special depreciation (Bonus Depreciation).  Section 179 (Bonus Depreciation) is strictly limited to nonresidential (commercial) property.

You may have categorized the expense incorrectly or if it’s trying to apply the De Minimis Safe Harbor or Safe Harbor for Small Taxpayers.

• If you entered the roof under a category like "Land Improvements" (15-year property) or "Personal Property" by mistake, the program will automatically trigger the 100% bonus depreciation because those classes do qualify.
• If the roof cost was relatively low (usually under $2,500), you can "expense" it immediately using the De Minimis Safe Harbor.  

1. Open or continue your return.
2. Under Federal tab, Click on Wages & Income, and then Click on Rental Properties and Royalties.
3. Edit the roof entry under Assets/Depreciation.  Make sure the "Asset Class" is set to Rental Real Estate Property or Residential Rental Property.
4. Select "No", if the program asks if this is "Qualified Improvement Property."  
5. If you're asked about "Special Depreciation Allowance," decline or "elect out" of it for that specific asset class (so it defaults to the 27.5-year schedule).

Note: You can only depreciate the business percentage of the roof's cost (e.g., if the room is 10% of the square footage, you only depreciate 10% of the roof cost).