BOSTON – Senate Democratic candidate Elizabeth Warren signaled Friday that she hasn’t voluntarily paid a higher income tax rate on her Massachusetts tax returns than required.

Republican U.S. Sen. Scott Brown’s campaign had pressed Warren on the issue after she criticized him for voting against a bill that would have increased taxes on millionaires.

“I paid my taxes and I did not make a charitable contribution to the state,” Warren said when asked if she opted to pay a higher 5.85 percent rate on her Massachusetts income tax, as allowed under state law, rather than the standard 5.3 percent rate.

Brown’s campaign said that he too has decided against paying the voluntary higher tax rate.

During an interview on WTKK-FM on Friday, Brown was also asked if he would release his tax returns. He said he would probably make public the last five or six years of returns that he and his wife, Gail Huff, had filed.

“I’m happy to, I’ve got nothing to hide,” he said. “Gail and I would certainly love to be transparent and in this position you need to be and if there are any questions, great.”

“So we’ll probably, we’re considering releasing six years, five-six years I don’t care, whatever,” he said. He did not indicate when he might make the returns public.

Warren has said she would release two years of returns if Brown did the same. On Friday, she said if Brown were to release more than two years, she would discuss the possibility of releasing more years.

The Brown campaign called Warren “hypocritical” for pushing for higher taxes for millionaires without saying whether she had voluntarily paid the higher state rate.