Can I deduct the new roof I put on my house?
"Can I deduct the new roof I put on my house?"
Yes, this credit ("deduction") was reinstated recently for 2019 and 2018 after not being allowed for 2018. So you'd have to amend your 2018 return to claim a 2018 credit.
The biggest catch with this credit is the lifetime limit of $500 after 2005. So maybe you spent $10,000 on a new roof in 2019. 10% of that cost (or $1,000) would be eligible for the credit. But obviously $1,000 is more than $500 so with that 1 purchase you've extinguished your $500 lifetime limit. This 10% rule also applies to the following items: windows, doors, skylights, roofs, insulation.
For water heaters, furnaces, and biomass fueled heaters, you're not limited by 10% of the cost BUT you are still limited to the same $500 lifetime limit. So if you're already bought that $10,000 roof, then you won't get a credit for buying the new water heater.
If, instead of buying the above items, you bought a solar water heater, wind turbine, geothermal heat pump, or a fuel cell, then you could deduct 30% of the cost of those items independently of the $500 lifetime limit. For 2020, you can only deduct 26% of the cost of these items.