The IRS said in its last note that it would be attempting to work with existing W-4 forms for now.
The standard federal W-4, which all employees fill out, is based on the notion of "allowances," which you could adjust based on your personal situation.
In the past, a single person with three children and a home in a high-tax state like New York might have listed themselves as married and claim one allowance per person, plus a few extra because they were likely to itemize their deductions and owe less. A married person with a freelance spouse who owes quarterly taxes might have listed themselves as single to have enough taken out to cover both of them.
The goal of people adjusting their withholding was to come as close as possible to paying the correct amount of tax - rather than owing money at the end of the year or ending up with a giant refund.
But it will all be different math for 2018.
"For first few weeks of January stay put, and see what the IRS comes out with," said Isberg, who also cautioned that employees should keep an eye on tax changes at the state level.
Above all, do not panic, said Farsheed Ferdowsi, president and CEO of Inova Payroll, which handles paychecks for more than 3,000 companies.
"When you have changes in taxes, it usually goes a lot smoother than most people know," Ferdowsi said. "If the first (paycheck) is wrong, it catches up on the next one."
This article was provided by Reuters.