(Bloomberg) -- Republican lawmakers said they wanted tosimplify the tax code so you could file your return on apostcard.

It turns out the new tax law will be anything but simplefor many affluent Americans, who are now inundating theiraccountants for advice.

They made it a lot more complex for a lot of people,” said JodyPadar, chief executive officer of New Vision CPA Group in Mt.Prospect, Illinois.

Clients are already asking how to exploit the changes, accordingto certified public accountants, lawyers and financialadvisers.

In some cases, the best advice is clear. For others, especiallybusiness owners, tax experts are scrambling to understand thefull implications of the 500-page law, which changes the rates onindividuals and corporations, and eliminates or limits manypopular deductions.

As a result, the new law could change the financial consequencesof major life decisions for millions of Americans, such as whoyou work for, whether you move or re-model your home, how you getto work, and even whether you get married or divorced. If you makea substantial amount of money, the right decisions could savethousands of dollars.

President Donald Trump signed the bill into law Friday. Thatallows the Internal Revenue Service to begin writingregulations on exactly how the law’s more complicatedprovisions—notably the deduction for pass-through businesses—wouldbe implemented.

But many advisers are already starting to plan, and calculateoptions, for their clients. Here are 7 areas affecting manypeople:

1. Business owners

Among the law’s most controversial and confusing provisions is anew 20 percent tax deduction for pass-through businesses, which areprivately owned firms whose owners pay individual rates on theincome they earn. That, along with a slashing of the corporatetax rate from 35 percent to 21 percent, is raising big questionsabout how to structure companies in 2018.

“I can’t believe this is going into effect in two weeks,” saidK. Davis Senseman, founder of the Minneapolis-based Davis LawOffice, who specializes in small businesses.

Senseman is in disbelief because a different corporatestructure might make sense for each of her 800 clients, she said.And that means each of them needs to re-examine the situation fast.The earlier changes are made in 2018, the more potentialfor tax savings.

But even the U.S.’s leading tax experts say they don’t yetfully understand the implications of the new rules tocalculate which option is best for clients. Ananalysis by a dozen tax professors identified a number ofpotential loopholes created by the pass-through break, and by thelower rate on regular corporations known as “C-corps.”

“We know we’re going to spend a lot of time in 2018 thinkingabout entity structure and helping clients decide whether theyshould be in a C-corp or a pass-through entity,” said David ScottSloan, co-chair of global private wealth services at Holland &Knight in Boston. “We’re still trying to figure that out.”

The pass-through deduction could also create an incentivefor more workers to quit their jobs and become independentcontractors.

But the law also could complicate the taxes of manyAmericans who are self-employed now, including so-called gigeconomy workers such as Uber drivers, New Vision’s Padar said.

2. Estate planning

Another frothy area of planning next year will be aroundtransfers of money to heirs. The tax law maintains thefederal estate tax, but it doubles the amount of wealth that isexempt from the levy after death and a related tax on giftsduring a person's life. Starting in 2018, single people whodie with about $11 million would not be subject to the estate tax,up from $5.5 million. Married couples can shieldabout $22 million from estate and gift taxes.

That should keep Sloan busy. "We're lining up appointments forJanuary because of the tax-free gifting opportunities," hesaid.The higher thresholds expire in 2026 so some wealthy taxpayersmay want to move now to transfer more money to the next generationtax-free.

3. Paychecks

Many salaried workers across the U.S.—of varying incomelevels—will need advice on how much should be withheld from theirpaychecks next year after most of the law’sprovisions go into effect in January.

If they don't get withholding right, they could end up with abig tax bill in 2019 or an unnecessarily large refund, Padarwarned.

“That’s uncertainty for Joe taxpayer that, to me, is somethingto be unnerved about,” she said.

4. Commuting

Employees should also note that buried in the taxlaw are changes affecting commuters.

The tax law eliminates a break that currently allowscompanies to deduct some of the cost of providing parking andtransit passes. It also ends a $20 a month benefit to helpcover the costs of employees who bicycle to work.

The provisions could push employers to stop subsidizingtheir workers’ tabs for parking, mass transit and bikemaintenance.

5. Real estate

The legislation will also impact finances at home. That'sbecause it caps at $10,000 the amount of state and localincome and property taxes that taxpayers can deduct each year.

Groups representing the real estate industry have said they’reworried that this could lower home prices, especially in high-tax,high-cost areas of the U.S. Also affecting homebuyers is a new capon the mortgage deduction.

For new purchases of homes, the deduction would be capped atloan amounts of $750,000, down from $1 million.

In addition, the law ends a deduction for home equityloans, which could make it harder for homeowners to borrow tofund projects like home renovations.

6. Marriage

If you really want to maximize your tax situation, thelaw could even adjust your romantic decisions.

Under current law, many two-incomecouples end up paying more in taxes by getting married. The laweliminates that marriage penalty for couples making less than acombined $600,000.

So, if you've held off on gettinghitched because of a tax hit, 2018 may be your wedding year. But beadvised: Those individual tax-rate changes are set to end in 2026-- after that, your marriage might have to be just about love.

And top earners should still be awarethat marriage could be expensive at tax time. Adding to tax billsfor some couples is the cap on state and local tax deductions. It'slimited to $10,000 for married couples, even though two singlepeople can deduct $10,000 each.

7. Divorce

Tax considerations are even changing for those getting adivorce.

Under the law, divorced taxpayers who pay alimony would nolonger be able to deduct those payments from their income, andrecipients of alimony would also no longer need to report the moneyas income.

However, the provision doesn’t go into effect right away andinstead applies to divorces finalized after Dec. 31, 2018. So,depending on whether you’re set to pay or receive alimony, youmight want to speed up or slow down those divorceproceedings.

No matter what, accountants to affluent Americans aren't likelyto have a restful holiday season. “We don’t have a year tofigure it out,” said Greg Rosica, a contributing author to the EYTax Guide 2017. “We have to begin planning today.”

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