US Democratic presidential candidate Hillary Clinton and former President Bill Clinton on Friday released their 2015 tax returns, showing they made $10.75 million (9.63 million euros) in income and paid an effective federal tax rate of 34.2 percent. They also made $1 million in charitable contributions that same year.

Senator Tim Kaine, Clinton's running mate, and his wife also released 10 years of tax returns, showing they paid an effective federal tax rate of 25.6 percent and donated 7.5 percent of their income to charity.

"Hillary Clinton and Tim Kaine continue to set the standard for financial transparency," said Clinton's campaign aide Jennifer Palmieri in a statement.

"In stark contrast, Donald Trump is hiding behind fake excuses and backtracking on his previous promise to release his tax returns.

"He has failed to provide the public with the most basic financial information disclosed by every major candidate in the last 40 years," she added.

Trump awaiting IRS audit

Trump has refused to release his tax returns until an audit conducted by a special division known as the "Wealth Squad" of the Internal Revenue Service (IRS), the US' tax authority, is completed.

Although the IRS has said Trump can release his tax returns even while under audit, the Republican presidential candidate's special counsel Michael Cohen told CNN on Thursday that he would not allow him to do so until the "Wealth Squad" finishes its probe.

While they are not obliged to by law, it is customary for US presidential candidates to make their tax returns public. In some form or another, Clinton has made hers public for every year since 1977.

ls/cmk (Reuters, AP)