Can I deduct the cost of a radon-mitigation system that we installed in our home during 2016?

[jerry2000 · Accepted solution]

No. That is not deductible.
Repairs, maintenance, and improvements  to your personal residence property are not deductible from current income. If you make major improvements which increase your home’s market value or extend its useful life, you can add the cost of the improvements to the cost basis of your home, and you get the benefit when you sell.
You might find it helpful to read IRS Pub. 530, Tax Information for Homeowners
http://www.irs.gov/pub/irs-pdf/p530.pdf

and IRS Pub. 523, Selling your home
http://www.irs.gov/pub/irs-pdf/p523.pdf

[MikeSpalding]

The IRS did consider allowing this, but it is considered a home improvement.  You can use it to increase your basis when you sell your rental property and reduce capital gains.