The broad-ranging Tax Cuts and Jobs Act was passed so late last year that the Internal Revenue Service is still issuing interpretations of the law—and probably will continue to do so through the rest of this year. 

For individuals doing tax planning now—as many Americans do during tax season—the uncertainty can make for difficult decision-making. 

"Tax professionals are waiting for the official word on a variety of issues, the same way taxpayers are," says Hans Scheil, a certified financial planner and owner of Cardinal Retirement Planning, in Cary, N.C.

Still, experts say they can answer some gnarly common questions about the new tax law. 

Do the Taxes We’re Filing This Tax Season Reflect the New Tax Law?

For the most part, no. One exception affects households with very high medical bills, notes Jim Barnash, a CFP at SGL Financial, in Buffalo Grove, Il. The new tax law says qualified medical expenses that exceed 7.5 percent of your adjusted gross income can be deducted on your 2017 tax return. That's a lower threshold than the 10 percent allowed earlier.

Is Interest on a Home-Equity Line of Credit or Loan Still Deductible?

Maybe. Under the old law, which still applies to your 2017 tax return, you are allowed to deduct interest on up to $1 million in mortgage debt used to buy, build, or improve a main or second home, and $100,000 in home-equity debt used for any purpose.

Now, for interest to be deductible, the borrowings must have been used to buy, build, or significantly improve your main or second home. Deductible interest is limited to home mortgages and home equity debt totaling $750,000.

What's different now is you will be more limited in the interest you can deduct.

"You can still use a home-equity line of credit to purchase a car or pay off a credit card, but the interest is no longer deductible in these instances," notes Darren Zagarola, a certified public accountant with EKS Associates in Princeton, N.J.   

The new restriction applies to new and existing home-equity debt that's not related to building, purchasing, or improving your home. So if you took out money from your home in recent years to pay your child's college tuition, the interest related to that portion of your home-equity debt will not be deductible for tax-year 2018.

Notably, home-equity debt used toward your business still is deductible, says Dave Stolz, a CPA and member of the American Institute of CPAs Personal Financial Specialist Credential Committee in New York. 

Can I Continue to Deduct the Alimony I Pay?

Yes. If you're already divorced, you will still be able to deduct your alimony payments. The new law eliminates the deductibility of alimony for divorces executed or modified after Dec. 31, 2018. Alimony for divorces finalized this year will be deductible under the new law.

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Don't worry that you'll lose your tax deduction if you need to modify an existing divorce decree, says Joseph Brown, a family law attorney at Robinson & Henry in Castle Rock, Co.

"The original orders will still be governed by the laws in effect at the time those orders were entered," he says. But, he adds, the couple has the option of going by the new law when modifying their pre-2019 divorce. 

Will My Taxes Be Simpler to Prepare Next Year?

It depends. If you currently take the standard deduction, preparing your taxes next tax season probably won't change. If you itemize now and the new standard deduction—$12,000 for individuals, $18,000 for heads of household, $24,000 for couples filing jointly—is significantly higher than your 2017 itemized deduction, you'll likely take the standard deduction, which could make preparing taxes somewhat simpler. 

"For others it could be more complex, depending on their situation," Barnash says. It could pay to plan ahead.

For instance, some taxpayers could be on the borderline between itemizing and using the standard deduction for 2018. They'll need to talk to a tax preparer to get a sense of which way to go.

They could, say, double up on charitable gifts in even years to raise deductions to the point it's worth itemizing, and then reduce charitable giving in odd years to take the standard deduction.

"People should be using their 2017 income tax to forecast where they will be under the new tax law," Zagarola says.

If you own a small business, you'll want to determine whether you're eligible for the new tax law's beneficial tax treatment for so-called pass-through entities. The owner of a qualifying business can now exclude the first 20 percent of that business income if her total income is under $157,500 (or $315,000 if married, filing jointly). 

"Calculating deductible business expenses and other items that reduce taxable income will require planning throughout the year," Barnash says.

Should I Still Collect Receipts for Out-Of-Pocket Employee Expenses?

Maybe. "Generally speaking, out-of-pocket employee expenses are no longer deductible for federal tax purposes," says Cari Weston, director of tax practice and ethics for the American Institute of Certified Public Accountants, based in New York. "But there is no single answer that applies to every taxpayer."

An exception: Teachers in kindergarten through twelfth grade can still deduct out-of-pocket expenses up to $250. Disabled taxpayers who incur impairment-related work expenses also are still allowed to deduct those expenses.

Even if these situations don't apply to you, Weston says you still might want to continue tracking expenses.

"For one, if the expenses are substantial and the employer won't pay them or reimburse the employee, it may be worth a discussion come raise time," she says. "There is also the possibility that your state will still allow the deduction."

And while it's a long shot, a future tax law change could reinstate the deduction, Weston notes.

"If this were to happen, it is better to have the information readily available," she says. "And for nothing else, the current law expires in 2025 and it may be easier not to get out of the routine.”