When you make a home improvement, such as installing central air conditioning, adding a sunroom or replacing the roof, you can't deduct the cost in the year you spend the money. But if you keep track of those expenses, they may help you reduce your taxes in the year you sell your house.
For more info, see this detailed FAQ: https://turbotax.intuit.com/tax-tips/home-ownership/home-improvements-and-your-taxes/L6IwHGrx6