CNN

(CNN) - With tonight's domestic policy debate looming, both Barack Obama and John McCain debuted economic plans this week that they say will put more money in taxpayers' pockets. And both are hoping that instead of crunching the numbers, voters will let the campaigns do it for them.

The Obama campaign unveiled an online "tax calculator" Tuesday designed to highlight the Illinois senator's proposed tax breaks for the middle class.

Fill in a few details, and the tool calculates your savings.

A married couple filing jointly with $60,000 in income and two dependents, for instance, would enjoy $1000 in tax savings under Obama's plan, according to the calculator, versus $645 under McCain's. Take away those dependents, and the McCain number is reduced to zero.

"We expect that for the third debate in a row, John McCain will lie about Obama's tax plan," said Obama campaign spokesperson Nick Shapiro. With the tax calculator, he said, "the vast majority of voters will discover that they¹ll pay less in taxes with Obama as president."

The calculations get a little fuzzy for the highest wage earners: plug in an income of over $250,000, and the message pops up: "You will probably not get a tax cut under the Obama-Biden plan" something the Conservative group Americans for Tax Reform called "misleading" because it fails to mention any of Obama's plans for tax increases on high-income voters.

But two can play the numbers game: The Republican National Committee battled back with a "spend-o-meter" measuring how much they think Obama¹s new policy proposals will cost taxpayers.

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