Partly, but not in the way you probably think.
There is a difference between repairs and improvements. A repair restores property to as-was condition, while an improvement increases the value of the property or extends it's useful life. (Patching a leaky roof is a repair, while installing a whole new roof is an improvement.) Generally, improvements must have a useful life of more than one year. Also referred to as a "betterment" -- making the property better, compared with a repair that keeps it the same.
You generally don't get to deduct repairs that were made before you had rental income. You are supposed to keep your property in good repair and get no tax benefit for repairs made to your personal home, and there are limits on your ability to defer repairs until you start renting and then deduct them as expenses. The key date is the date you placed the property in service as a rental -- when was it advertised and available to rent. That's when you can start deducting repairs. You also can't really deduct repairs if you you have no rental income. If you started renting the home in 2016, then any repairs you made in 2015 would only be deductible on your 2015 tax return and then only if you had rental income. Any repairs you made in 2016 would be deductible if they were made after you placed the property in service.
Improvements are handled differently. Improvements add to the cost basis of the home, and become part of the basis for depreciation. Residential rental property is depreciated over 27.5 years, so if your depreciation basis was $100,000, you get a depreciation deduction of $3,636 per year that compensates you for wear and tear.
Your basis for depreciation is whichever is lower; your cost basis, or the fair market value at the time you place the property in service.
So let's assume you bought the home in 2010 for $100,000, and you made $10,000 of improvements (new furnace, roof, etc.) and the market value when you start renting it is $125,000. Your basis for depreciation is $110,000, which you deduct over the 27.5 year recovery period. So that's how you "deduct" the value of improvements, and it doesn't matter whether the improvements were made before or after you decided to rent the home out.
You will need to keep excellent records of your repairs for 7 years, and your improvements for as long as you own the property plus 7 years after that, so you can document and support your expenses, deductions, and tax returns.
