Teresa Heinz Kerry (search) may be the richest potential first lady ever to hit the campaign trail, having earned more than $5 million in taxable and non-taxable income last year.

The campaign of her husband, Massachusetts Sen. John Kerry (search), released Heinz Kerry's personal tax information on Tuesday, after revealing that she received an extension to file her 2003 federal income tax return.

Heinz Kerry, who files her returns separately from her husband, said she will make available the first two pages of her 1040 when it's filed in October.

Of the $5.115 million in income, about $2.3 million of dividend and interest income was taxable while another $2.7 million came from tax-exempt state, municipal and other public entity bonds.

Heinz Kerry paid $750,000 toward her 2003 federal, state and local income tax liability at the time of the extension filing, or about 32 percent of her gross taxable income.

Of that sum, $587,000 is estimated for federal income taxes; $162,777 is estimated for state and local income taxes, and Heinz Kerry paid an additional $280,000 towards expected 2003 and 2004 federal tax liability.

Heinz Kerry had resisted releasing her tax filings, saying most of her income is in trust funds with her children's names on them and it would be unfair to them to reveal their wealth.

"While I am not a candidate for any public office, a great deal of my financial information has been disclosed for many years on my husband's Senate Ethics Disclosure, and now that he is a presidential candidate, with the Office of Government Ethics," she said. "John and I believe this strikes a balance between my family's privacy and the media's requests for more financial information."

Kerry, who mortgaged their Boston townhome to keep him in the Democratic primary race last winter, paid $90,575 in federal taxes on $395,338 in adjusted gross income last year, according to copies of his federal returns released last month by his presidential campaign.

Heinz Kerry's exact wealth is not known, but has been estimated to be upwards of $500 million. She is the heiress of the Heinz Co. fortune, and runs the Heinz Family Foundation (search), which distributed $4.6 million in charitable contributions last year. Heinz Kerry runs the non-profit corporation, which she and her late husband, Pennsylvania Republican Sen. John Heinz, created before his death in 1991.

Heinz Kerry also is chairman of the Howard Heinz Endowment and a board member on the Vira I. Heinz Endowment, both were established by earlier generations of the Heinz family and make significant annual charitable grants. She does not have any managerial or other role with the H. J. Heinz Company or its company-directed foundation.

Fox News' Sharon Kehnemui and Catherine Loper contributed to this report.