And now the federal government, in the name of helping working families, may increase her financial burden.

In past years, the West Valley grandmother has been able to file her federal income tax returns as a head of household, a designation that allows her to pay less than if she filed as a single person.

But Anderton and a number of other low-income families in Utah could lose that benefit and others designed for people who support children. When they file their 2005 return early next year, the families could owe hundreds or even thousands of dollars more than they expected to pay, thanks to the paradoxically named Working Families Tax Relief Act of 2004.

"There are going to be a number of people who are going to be absolutely shocked by how this affects them," said tax attorney and author Kaye Thomas of Chicago-area Fairmark Press Inc.

In Utah alone, accountants estimate that between 29,000 and 48,500 of the state's 970,000 taxpayers could be negatively affected by the act, which was designed to simplify tax code and curb abuses of benefits such as the Earned Income Tax Credit.

But finding answers right now can be difficult. Several accountants said they are still trying to figure out the effects of the tax law changes.

"This is a tough issue for even our tax pros to sort out," said Steve Moore, an enrolled agent with H&R Block in Salt Lake City. "So you can imagine this is going to be difficult for a lot of low-income families who aren't going to understand how the new rules affect them."

IRS spokesman Bill Brunson said not all taxpayers will be hurt. Some foster parents, for example, stand to benefit. But he acknowledges there will be a number of taxpayers who will owe more tax. Yet when asked for more specifics, Brunson's advice was to call a tax accountant.

One thing is clear: Those most affected by the changes won't be the wealthy.

The changes won't affect any moderate- to high-income traditional two-parent households, because those types of families do not rely on head-of-household filing status and the Earned Income Tax Credit, said Rick Holbrook, tax specialist with H&R Block in Salt Lake City.

Two categories of people who will be most affected:

l A man who lives with a woman and her two children who are not his. Under the new tax law, the man no longer can file head of household or get the Earned Income Tax Credit, both of which reduce the family's tax burden by as much as thousands of dollars a year. The man and his girlfriend would have to get married to avoid paying what could be thousands of dollars more in taxes, Holbrook said.

l A family made up of a woman, her adult daughter and a grandchild. Under the old law, the woman could claim her daughter and grandchild as dependents, saving thousands of dollars, while her daughter still could claim the Earned Income Credit. The new law, however, places more restrictions on how those benefits can be distributed.

Another category of filers who may be affected includes single parents with adult children living at home. There is some question about whether those parents can file as head of household or receive other tax benefits if the children earn more than a certain amount of money. However, tax accountants are divided on what degree - if any - those families will be affected.

What worries Holbrook is that many families who will pay more tax won't know about the changes until they file their taxes - too late to change their withholding to allow for more taxes to come out of their paychecks and avoid writing out a bigger check in April. Holbrook urges people who may think they are affected to contact the Internal Revenue Service or an accountant now.

Salt Lake City accountant Gail Anger is concerned that the taxpayers who may be the most affected are the ones who do not consult an accountant until tax time.

Anderton is worried she may owe more than she can afford to pay in April and plans to contact the company that does her taxes each year to see whether there is anything she needs to do before tax season. "I hope they can figure it all out for me," she said.

Tax relief

* What is it? Changes in federal income tax code as part of the Working Families Tax Relief Act of 2004. Some lower-income families could owe hundreds, even thousands, of dollars more in taxes for the 2005 filing year.

* Who is affected? Various estimates show 3 percent to 5 percent of about 970,000 Utah taxpayers could face higher tax bills.

* What should you do? If you think you may be affected, consider having more tax withheld from your paycheck. But first, consult the Internal Revenue Service at www.irs.gov or 1-800-829-1040 or a tax preparer.