Apr. 19--Wage earners beware: One of the federal government's new tax breaks, designed to put more take-home pay in your wallet now, may take a bite out of your wallet next spring.

Under certain conditions, the extra cash you've started seeing in your paychecks could shrink your refund or boost the size of the check you have to write when you file your 2009 tax returns next year.

How can that be? Simply put, your employer may be giving you too big a break on your withholding taxes under the government's "Make Work Pay" stimulus plan if you're a two-income couple or an individual working two jobs.

Working couples, for example, qualify for a tax credit of as much as $600 this year, doled out in small amounts in each paycheck through lower payroll-withholding rates required by the government. Ideally, each spouse's employer should lower the withholding rate enough to generate a $300 tax credit for each person.

But that's not what is happening.

The two employers are both applying the lower withholding rates, which means the couple will actually have a combined $1,200 left in their paychecks between now and the end of the year. When they do their taxes next spring, they could find they owe more, or are getting back less, than they expected.

Quick cash to aid economy Why are companies doing this? Well, it's efficient and quick. They don't have to take extra time to verify your spouse's employment status. And the government wants it that way.

Uncle Sam isn't nearly as concerned about the tax consequences for you next spring as much as he is in getting extra spending money into people's hands now in hopes of boosting the economy, which is in its worst recession in a quarter-century.

"We pretty much agree with the government's idea of doling out stimulus the quickest way possible, by way of reduced withholding taxes," said Steve Mezistrano, chief of government relations for the American Payroll Association, which represents U.S. employers. "But there is some fallout to deal with, especially if you are a dual-income married couple or individual who works two jobs."

Fortunately, you can avoid the problem by doing two things:

-- First, figure out how much you should have withheld from each paycheck to fulfill your estimated 2009 income-tax bill. Many financial Web sites will help you do that; H&R Block offers a "2009 Making Work Pay Calculator" on its Internet site, hrblock.com.

-- Second, have your employer adjust your payroll withholding to ensure you're getting at least enough tax taken out each pay period to cover your estimated tax total.