If you used your second home for personal use, IRS does not allow any deductions on the improvements. You can only add those improvement expenses to the cost basis of your property when you sell it. However, if you used it for business use, for example rental, then you can deduct the capital items by depreciating them over a period of time instead of all at once.
For personal-used home, by adding the amounts you spent on the upgrades to the
original purchase price would increase your basis of the property, therefore
lower the taxes by reducing the gain. If you sell the property for a loss, your cost basis is the lesser of (1)
the Fair Market Value or (2) the Basis (usually the purchase price plus cost of
improvements). However, the basis for a GAIN is the actual
Basis. The Fair Market Value is not used if it is sold at a Gain.
For business-used or rental property, see information below:
https://ttlc.intuit.com/replies/4791833
