New York (CNN/Money) - There's tax relief in sight next year, modest though it may be, for millions of Americans in the upper brackets, according to CCH Inc.

The tax law publisher Thursday reported taxpayers in the 27 percent and higher brackets will owe slightly less in 2003, thanks to projected inflation adjustments by the IRS. The U.S. tax code requires federal income tax brackets to be adjusted for inflation annually.

According to CCH, a married couple with a taxable income of $100,000 will save an estimated $90 in income taxes next year, while single filers with taxable incomes of $50,000 would see their tax tab fall by $54.

Here's why: If you're in the 27 percent tax bracket, only the top tier of your income is taxed at that rate. The first $6,000 you earn (for single filers) would be taxed at 10 percent. The next portion of your income, up to $27,950, gets taxed at the 15 percent rate, and anything beyond that up to $67,700 gets hit with 27 percent.

When it's indexed for inflation, you're able to earn more before your income gets bumped into the next highest bracket, said George Jones, a senior federal tax analyst at CCH.

In 2003, for example, a married couples' taxable income can be as much as $311,950 and still fall into the 35 percent bracket. This year, if they earn that much their highest bracket is 38.6.

Federal income tax brackets are required to be adjusted for inflation annually. The adjustment is based on Consumer Price Index figures for September through August immediately prior to the adjusted year. CCH's projections are based on the inflation data released Wednesday by the Labor Department.

As it turns out, however, the tax code doesn't index all items. The new 10 percent bracket, for example, will hold steady at $6,000 for singles, $10,000 for heads of households and $12,000 for joint filers. CCH said indexing for this low rate doesn't kick in until 2007.