It could put a serious dent in your wallet.

The Government Accountability Office in Washington has issued a new report that finds about 30 million people, which is 21 percent of workers in New Jersey and across the country, are not having enough taxes withheld from their paychecks under the federal tax law changes that were adopted last year.

This compares to 18 percent being underwithheld before the tax law changes were passed.

Jack Tinari, a CPA at CSI Group, said this means some Garden State residents who are getting more money in their weekly paycheck now will wind up owing money to the Internal Revenue Service next year.

“We had warned everybody back in February and March to make sure they had changed their withholding," he said.

He said for some people this is adding insult to injury because “our deductions are now being limited, taxes have increased — on top of that our withholdings have dropped, and it spells for a recipe for disaster.”

Most New Jersey residents who will adversely affected by this situation “are the people who have over $10,000 in real estate taxes and state income taxes that were normally itemizing deductions.”

“The income levels probably hardest hit are probably from $130,000 if you’re married, to around $200,000."

He said another thing you need to be aware of is people who are used to getting large refunds may be in for a surprise next year. For example, someone used to getting a $5,000 refund could end up with $3,500.

Tinari said there is no one guideline that is right for everybody. He recommends talking with your tax preparer to review what’s being withheld from your paycheck so you don’t wind up owing a lot when you’re not expecting it.