What a difference year makes.

For the 2012 tax year, you can take a tax deduction on medically necessary home improvements — like installing a wheelchair ramp and other projects that make life easier for an ill or injured family member — if you:

• Itemize deductions

• Spend more than 7.5% of your adjusted gross income on the upgrades (10% of AGI if you’re subject to alternative minimum tax).

Starting in 2013, if you’re under age 65, you can’t take the tax deduction on medical expenses until you spend 10% of your AGI. But if you’re 65 or older in 2013, you can stick with the 7.5% AGI tax deduction threshold through the end of 2016.

The rules for tax deductions on medical home improvements are tricky:

1. Start with what it costs to modify your home.
2. Subtract the value the upgrades add to your home.
3. What’s leftover is your tax deduction — if you meet your AGI threshold.

How it works

Say you’re 45 years old and spend $20,000 to put a bathroom on the first floor of your home because your husband can’t climb stairs anymore. Your AGI is $100,000. A REALTOR® says the bathroom adds $10,000 to the value of your house.

1. Start with the cost of the improvements: $20,000
2. Subtract your added home value: $10,000
3. Of that $10,000 difference, you can only take a deduction for expenses that exceed 7.5% of your AGI or $7,500.

So if you itemize, you can take a $2,500 deduction for the 2012 tax year. Wait until 2013 and you get no deduction because your threshold rises to 10%. If you’re over age 65, though, you can claim a $2,500 deduction.

Tip: Doing all your improvements in a single year will help you meet the AGI threshold.

Some of the improvements that you can claim a tax deduction for, according to IRS Publication 502, “Medical and Dental Expenses”:

• Entrance ramps for your home

• Grading the yard before building a ramp, or to make it easier to get in your home

• Widening exterior or interior doorways

• Widening or removing hallways

• Installing railings, support bars, or other bathroom improvements

• Lowering or modifying kitchen cabinets and equipment

• Moving or modifying electrical outlets and fixtures

• Installing porch lifts and other forms of lifts (but elevators generally add value to the house)

• Modifying fire alarms, smoke detectors, and other warning systems

• Modifying stairways

• Adding handrails or grab bars anywhere (whether or not in bathrooms)

• Changing door knobs

• Upkeep of medically necessary upgrades, like elevators, and operating costs

• Lead-based paint removal if your child has lead poisoning

• Renovating an existing bathroom to make it handicap accessible or adding a new accessible bath

Will the tax change encourage you to make necessary changes this year?