The new tax law that went into effect in 2018 nearly doubled the standard deductions. As a result, only 13.7 percent of taxpayers are expected to itemize expenses on their 2019 returns, according to the not-for-profit Tax Foundation. Prior to the enactment of the Tax Cuts and Jobs Act, nearly one-third of filers itemized expenses to reduce their taxable income.

Many taxpayers may think they can itemize expenses that aren’t really deductible, such as over-the-counter medicines. There are steps you can take to reduce your tax bill, but if you try to claim illegitimate write-offs, you could end up paying the government interest and penalties.

“This denial of deductions will also likely be reported to state income taxing authorities and could have state income tax implications,” says tax expert Francine J. Lipman, a professor at the William S. Boyd School of Law at the University of Nevada, Las Vegas.

Unless you have enough deductible expenses to surpass your standard deduction, you cannot itemize. The standard deductions for 2019 are $12,200 for single filers; $18,350 for heads of household; and $24,400 for married couples filing jointly.

To help you avoid missteps, we’ve put together a list of expenses you might think you can claim but can’t. We also list related tax breaks that are legitimate.

Here are nine expenses you can’t deduct, along with nine related expenses that are deductible for the 2019 tax year.

1. Over-the-counter medicines (unless a doctor prescribes)

Headache and cold remedies you buy at the pharmacy are not tax-deductible. Only medicines prescribed by a doctor, including insulin, are considered deductible.

But you still can deduct over-the-counter kits to test for pregnancy and blood-sugar levels. And the IRS says moms get a tax deduction on breast-feeding supplies, including pumps and bottles.

2. Volunteer work (unless you rack up mileage)

You can’t claim the monetary value of the hours you spend volunteering for a nonprofit. Nor can you deduct the value of a project you create for charity, such as a poster or T-shirt.

But you can deduct the miles you drive doing charity work at the rate of 14 cents per mile, unchanged from 2018. Keep good records of your miles logged for charity work.

You also can claim unreimbursed out-of-pocket expenses, such as poster boards and special markers you bought for the nonprofit’s poster project. Be sure to keep your receipts.

It’s smart to have a credit card that you can use exclusively for purchases tied to volunteer activities.

3. Landlines and cellphones (unless business-related)

If you still have a landline telephone at home, you can’t deduct the cost, even if you primarily use that phone for business. The IRS says the first hard-wired phone line in your home is considered a nondeductible personal expense.

But you can deduct as a business expense the cost of business-related long-distance charges on that phone. And if you have a second landline phone specifically for business use, its full cost is deductible.

Cellphones are a legitimate deductible expense if you’re self-employed and use the phone for business. It’s recommended that you obtain an itemized bill to prove it.

However, the “unreimbursed business expense” deduction for using a personal cellphone for work has been eliminated. And if your employer provides you with a cellphone as part of your job, this could increase your taxable income.

4. Family pet (unless it’s a service animal)

A little family dog can result in some big bills. It’s not unusual to hear of pet owners spending thousands of dollars for surgeries, X-rays and prescription medicines for their animals. But those expenses are not tax-deductible.

However, the cost of buying, training and maintaining a guide dog or other service animal for someone who has a physical disability is tax-deductible. This generally includes any expenses incurred to maintain the animal — including for food, grooming and veterinary care — so that it can perform its duties.

5. Commuting costs (unless it’s for a temporary job)

The cost of getting to and from work is not tax-deductible. Taking a bus, subway, taxi or driving your own vehicle to work is a personal expense, regardless of how far you have to travel.

But you might be able to deduct some commuting costs if you work at two places in one day, whether or not it’s for the same employer. You also can deduct transportation expenses between your home and a temporary job that is expected to last one year or less.

And if your home is your main workplace, you can deduct transportation expenses for going from your home to another work location in the same trade or business.

6. Social Security taxes (unless you overpay)

You fork over a lot of money each payday for FICA (Federal Insurance Contributions Act) taxes, which fund Social Security and Medicare benefits. FICA taxes are not deductible.

But if you overpaid the tax, you can get a credit for FICA over-withholding. For 2019, the maximum in Social Security taxes is $8,239.80, an increase of $279 from 2018.

The wage base limit for 2019 rises to $132,900, up $4,500 from 2018. You pay FICA taxes only on wages up to the limit. If you had more than one job and your combined earnings exceed the wage base limit, you might have overpaid FICA taxes, in which case you may be able to request a refund or a tax credit.

7. Plastic surgery (unless medically necessary)

Face-lifts, liposuction, electrolysis and other procedures done to enhance your appearance are not deductible medical expenses.

But if your doctor says you need a nose job to treat respiratory problems, for example, it becomes a deductible medical expense.

The IRS says you can deduct the cost of plastic surgery if it is necessary to improve or correct a deformity resulting from a congenital abnormality, an injury incurred in an accident, trauma or a disfiguring disease.

8. Cost of work wardrobe (unless it’s a uniform)

Looking sharp at work rests totally on your shoulders. A U.S. Tax Court ruling in 2011 reaffirmed this tax law when a judge rejected a TV anchorwoman’s efforts to deduct tens of thousands of dollars in clothes she bought to wear on air.

But you can deduct the cost of dry cleaning or laundering of business uniforms, because it’s attire you can’t wear anyplace but work.

Also deductible are cleaning charges for nonprofit uniforms, such as an outfit required of hospital volunteers, or Boy Scout or Girl Scout troop leaders. Here, the costs of the uniform and its maintenance would be considered charitable deductions.

9. Summer camp for your kids (unless it’s day camp)

When school lets out for the summer, working parents fret over what to do with the children while they’re at work. Some parents send their kids off to camp because it’s fun for the children and eases their child-care concerns. But sleepaway camps are not tax-deductible.

However, if you decide to send the kids to a day camp during the hours you’re working or looking for a job, that expense could qualify for the child- and dependent-care credit.

For one child, you can count up to $3,000 of expenses toward the credit for 2019. If you paid for the care of two or more dependents, the credit limit is $6,000.

Your actual tax credit can be up to 35 percent of your qualifying expenses, depending on your income. Since it’s a credit, you can use it to offset your tax bill, dollar for dollar.

If you’re getting a tax refund, consider where you should park it.

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