If you are looking for a way to lower your taxes and have already worked your way through well-known deductions such as child-care expenses and property taxes, it may pay to think outside the box.
There are some write-offs you may not have known about, and those could apply to your situation.
That could come in handy if you are nearing the new, higher threshold for the standard deduction. Under the new Tax Cuts and Jobs Act, it is now $12,000 for single filers and $24,000 for married couples filing jointly.
"If you are close and you weren't aware of any of these deductions, you could possibly push yourself over the standard deduction and be able to take itemized deductions and possibly more of them," said Lisa Greene-Lewis, a CPA and tax expert with TurboTax.
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The higher standard deduction, along with the cap or elimination of some deductions, means more people will forgo itemizing. TurboTax estimates about 90 percent of people will use the standard deduction for 2018.
For those estimated 18 million people who likely will still itemize, they need to be sure to have information that backs up their claim, such as doctors' notes for medical conditions. And they generally need to work with an appropriate tax expert.
"Be careful about advice," said Jackie Perlman, principal tax research analyst at The Tax Institute at H&R Block. "Your deductions have to be legitimate."
With that in mind, here are five under-the-radar ways to save on your taxes.
1. Wedding costs 
Getting married can be expensive. The average cost of saying "I do" in the U.S. is $33,931, according to a recent survey by wedding planning website The Knot.
While you can't just deduct most wedding costs, there are some related expenses that could qualify — if you hit certain criteria. For example, if you hold your wedding at a registered historical location, you can deduct the price you paid to the site.
"They look at that also as a charitable contribution, like you are donating money to the historical site for upkeep," Greene-Lewis told CNBC.
You can also save on your taxes if you donate your wedding dress or any decorations from the big day.
As with any charitable giving, make sure you get receipts.
2. Historic preservation of your home 
That old fixer-upper you bought could wind up being eligible for a historic preservation credit on your tax return.
The federal credit is mainly for commercial properties, but depending on where you live, you may be able to get a state historic tax credit. Details vary, but 23 states provide tax credit for owner-occupied homes, according to the National Trust for Historic Preservation.
To qualify, the house must be recognized on the National Register of Historic Places, Greene-Lewis said. That means it has to hit certain criteria, such as being associated with an event or person that made a significant impact in history or embodying certain characteristics of a type, period or method of construction. To start the process of registering your home, first check with your state's historic preservation office.
3. Out-of-pocket charitable expenses 
Charitable donations are a well-known deduction; however, it can be more than giving away an item or straight-up cash to a nonprofit organization.
If you donate your time — such as traveling to Alabama after the recent tornado to help with the recovery efforts — you can write off out-of-pocket expenses, such as the mileage you put on your car.
"You have to keep excellent records — where you went, what you were doing, who you were assisting, and so on and so forth," Perlman said.
4. Weight loss and antismoking aids 
If you have a medical condition such as heart disease or diabetes and your doctor prescribes a lap band or a weight-loss program, you may be able to claim a medical deduction, Greene-Lewis said.
The same goes for treatments to stop smoking. You can deduct the cost of a cessation program or acupuncture if it is to alleviate nicotine withdrawal — as long as you have a prescription.
The bottom line with any medical deduction: Make sure you can back it up.
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"They should make sure they definitely have a doctor's note saying that the doctor prescribed whatever it is to mitigate disease or to help them with the disease," Greene-Lewis said. "Then, of course, save any receipts from their doctor visit and make sure they weren't reimbursed through their insurance for anything they are claiming."
Perlman agrees that, with any medical deduction, unless it is something clearly medical, like crutches or prescription medication, "you need some convincing evidence for your particular medical condition and that it relieves your condition and that nothing else would really do."
It's also important to note that when it comes to medical expenses, you can only deduct the amount that exceeds 7.5 percent of your adjusted gross income for 2018.
5. Defaulted personal loans to friends
