The federal budget deficit-reduction plan Walter F. Mondale is to unveil today calls for budget cuts and tax increases of roughly $175 billion in fiscal 1989, and will include a "pay-as-you-go" pledge that any new programs proposed by a Mondale administration would be financed by spending cuts or tax increases, sources familiar with the plan said yesterday.

The sources also said that tax increases account for slightly less than half of the deficit package and would be earmarked for deficit reduction, rather than for additional government spending.

That commitment, Democratic strategists say, is designed to inoculate Mondale against the expected Republican charge that the tax increase proposals represent a rerun of past Democratic "tax and spend" policies.

In his weekly paid radio address yesterday, Mondale repeated his contention that no matter who wins the presidency, taxes will have to be raised next year to close the "nearly three-quarters of a trillion dollars" deficit that the Reagan administration has built up.

"Everyone knows that taxes will go up. But who will pay?" Mondale asked. "If you have a president who favors millionaires and big corporations, he'll sock it to the families of average income and leave his friends alone. That's Mr. Reagan -- not me."

Campaign chairman James A. Johnson said in an interview that tax increases will fall most heavily on those in the upper-income brackets.

A tax plan Mondale presented in January, which would raise $60 billion in new revenues by fiscal 1989, called for a 10 percent surcharge on incomes over $100,000, the deferring of indexation of tax brackets to inflation (with protection for low- and moderate-income taxpayers), a cap on the 1981 tax cut for incomes above $60,000 and a 15 percent minimum tax on corporations.

The tax bite will increase in the new Mondale plan because he has committed himself to reducing the federal deficit by two-thirds by 1989, rather than by half, as promised in January.

Morever, the new plan would cut two-thirds from a 1989 deficit estimated by the Congressional Budget Office to be $263 billion.

The Reagan administration has projected a $162 billion deficit for that year, but Mondale has called that estimate "blue smoke and mirrors" and relied on the higher CBO figure.

Johnson said yesterday that the new Mondale plan contains only a "slight" increase in the tax burden on middle-income taxpayers. Mondale has ruled out a national sales tax and value-added tax, options that would fall heavily on moderate-income taxpayers and that President Reagan has said he would consider as a "last resort" to close the budget deficit.

The "pay-as-you-go budgeting" plan Mondale will unveil has been proposed in various forms in Congress over the last several years by both Democrats and Republicans, but it has never been enacted.

One risk of such a commitment is that Mondale has made numerous promises -- some general and some specific -- that call for new expenditures.

Among them are his pledge to rebuild the nation's highways, ports and water systems; to restore cuts in environmental agencies and in social spending for the poor and elderly; to reinvest in the nation's public schools and to launch programs to guarantee the country's preeminence in research and competitiveness in world trade.

Mondale's January deficit-reduction package included some $30 billion in new spending for such programs, but they were more than offset by $70 billion in proposed spending cuts, with half that amount coming from the defense budget and the rest from agriculture programs, health care costs and interest payments.

In his radio address, Mondale said that the difference in the budget cuts he would impose and those favored by Reagan revolve around a question of "the president's values."

"If he believes that investing in education is a bad idea, he'll cut it. If he thinks that people don't really depend on Social Security, he'll cut it. That describes Mr. Reagan pretty well -- but not me."