She also hit Sanders for his relentless focus on income inequality, saying that she, too, has a long history of addressing the issue -- but "it's not the only thing I talk about."
The Democratic presidential contender's comments came in an interview with CNN's Alisyn Camerota after a campaign stop at Iowa State University, where Clinton had turned her stump speech into a sustained attack on Sanders on guns, health insurance, taxes and more.
"Sen. Sanders has some very big ideas, but he hasn't yet told anybody how he would pay for them," Clinton told Camerota.
"And he had promised that he would roll out his tax plans before the Iowa caucus on February 1," Clinton said. "Well, if you wait too long, nobody will have a chance to see them or analyze them."
She added: "I am very clear about what I would do and how I would pay for it."
Clinton's criticism comes amid an increase in the frequency and sharpness of her attacks on Sanders, her rival for the 2016 Democratic presidential nomination. Two polls released Tuesday show Sanders leading Clinton in both Iowa and New Hampshire, the first two states to vote in the nominating contest.
Sanders has pledged to offer a tax plan ahead of Iowa's caucuses on February 1, but he hasn't set a date for its release.
Clinton, meanwhile, has proposed a raft of programs -- including paid family leave, debt-free college tuition and caps on prescription drug costs -- that her campaign estimates would cost $100 billion annually. She'd pay for those with a 4% surcharge on Americans who earn more than $5 million, as well as implementing a minimum tax rate for those who earn more than $1 million and limiting tax deductions to 28% with an exception for giving to charity.
Clinton also pushed back on Vice President Joe Biden's characterization of her as a newcomer to the fight over income inequality when compared to Sanders.
Biden, in an interview with CNN's Gloria Borger on Monday
, said that "it's relatively new for Hillary to talk about" income inequality, even as he credited her with having "come forward with some really thoughtful approaches to deal with the issue."
"I have been on this issue in many different ways -- how do we make education more equal, how do we make health care more equal? Of course that's tied to income equality," she said. "But there's also a broader range of issues that I have a long record addressing."
She pointed to work as New York's senator on limiting corporate executive pay, derivatives and credit default swaps, saying she "stood up to Wall Street. I called them out."
Then, in a clear shot at Sanders, Clinton said: "I have a broader agenda. It's not the only thing I talk about, because I think you have to view the quality of opportunity and how we deliver that in the 21st century from many different perspectives. And that's what I try to do."
Clinton said she didn't see Biden's comments as a sleight because during her tenure as secretary of state, she wasn't commenting on domestic politics issues at all.
Biden later clarified his remarks in an interview on NBC's "The Today Show"
"What I meant was, for the last five years, she's been engaged in foreign policy," he said.
Clinton said she avoided domestic politics while serving as secretary of state.
"So yes, for four years, despite a long career both in and out of public service, where I have been relentless in talking about these issues, there were four years when I did not," Clinton said.
"I talked about how we're going to get Iran to the negotiating table and try to prevent them from getting a nuclear weapon; how we're going to, you know, deal with a rise in China; what we're going to do about women's rights, something that goes to the heart of inequality," she said. "So I had a different agenda because I had a different job."
In the interview, Clinton once again deflected questions about Republican presidential front-runner Donald Trump calling her an "enabler" of Bill Clinton's sexual improprieties.
"I have no response. I'm going to let him say whatever he wants to say. He can run his campaign however he wishes," Clinton said, pivoting into a criticism of Trump's opposition to equal pay and minimum wage laws.
Pressed on whether she should respond to Trump's characterization of her as an enabler of sexual assault -- particularly since Clinton has said survivors of sexual assault should be believed.
"I'm going to let the voters decide what's relevant and what's not relevant in their decision as to who they're going to support," Clinton said.
She did say, though, that "it would be amazing" to run against Trump in a general election.
She said if she wins the Democratic nomination, she would immediately begin work "right then and there" on "how we organize the White House, how we organize the Cabinet, what's the legislative agenda" -- even before the general election.
"You know, the time between an election and an inauguration is short. You can't wait. I mean, you can't take anything for granted. You have to keep working as hard as you possibly can. But I think it's important to start planning," Clinton said. "Because we know what happens if you get behind in getting your agenda out and getting your appointments made. You lose time."