Labour has stepped up its attack on the government over planned changes to child benefit and working tax credits.
From April, couples with children who work part-time will have to increase their weekly hours from 16 to 24 to be eligible for tax credits worth thousands of pounds a year.
But Labour MP Catherine McKinnell branded the plans "crippling" and her party colleague Jessica Morden demanded to know where the "mythical" extra hours would come from, during Treasury questions on 6 March 2012.
Ms Morden said the government had "no real understanding" of the difficulties facing families having to find extra work.
Economic Secretary to the Treasury Secretary Chloe Smith defended the government's plans, maintaining the changes would target benefits at "those most in need".
She insisted there were enough jobs for parents to work an extra eight hours a week to qualify for tax credits.
Addressing the Commons Ms Smith said: "Vacancies were up 11,000 in the last three months to January 2012. There was a total of 1.07 million (people) moving into employment in the last quarter."
She said mothers and fathers who stand to lose money as a result of the changes should "take a very clear look around at the opportunities available throughout the economy".
But shadow chief secretary to the Treasury Rachel Reeves accused Ms Smith of "complacency" and claimed that people would be better off out of work than in employment because of the government's "crazy ideas".
Ms Smith attacked Labour's record, telling MPs the previous government allowed nine out of 10 households to be eligible for tax credits which was "unsustainable" and "uncontrolled spending".