Depreciation on your home is deductible only if you use your home for business.
Per IRS Publication 587 Business Use of Your Home (Including Daycare Providers)
, page 9: Figuring the Depreciation Deduction for the Current Year.
If you began using your home for business before 2017, continue to use the same depreciation method you used in past tax years. However, if you figured your deduction for business use of the home using the simplified method in a prior year, you will need to use the optional depreciation table for modified accelerated cost recovery system (MACRS) property. See Pub. 946
for the optional depreciation tables. For more information about the simplified method, see Revenue Procedure 2013-13, 2013-06 I.R.B. 478, available at www.irs.gov/irb/2013-06_IRB/ar09.html
If you began using your home for business for the first time in 2017, depreciate the business part as nonresidential real property under MACRS. Under MACRS, nonresidential real property is depreciated using the straight line method over 39 years. Page 10: Depreciating Permanent Improvements.
Add the costs of permanent improvements made before you began using your home for business to the basis of your property. Depreciate these costs as part of the cost of your home as explained earlier. The costs of improvements made after you begin using your home for business (that affect the business part of your home, such as a new roof) are depreciated separately. Multiply the cost of the improvement by the business-use percentage and depreciate the result over the recovery period that would apply to your home if you began using it for business at the same time as the improvement. For improvements made this year, the recovery period is 39 years. For the percentage to use for the first year, see Table 2.