Shadow chancellor refuses to rule out using threshold to raise money . Vows not to hike income tax rate but not trapping more people in 40p rate . Chancellor George Osborne says Balls has 'let the cat out of the bag . Tories promise to raise threshold from £41,865 to £7billion by 2020 . Labour says the plan amounts to a £50,000 unfunded commitment .
Shadow chancellor refuses to rule out using threshold to raise money . Vows not to hike income tax rate but not trapping more people in 40p rate . Chancellor George Osborne says Balls has 'let the cat out of the bag . Tories promise to raise threshold from £41,865 to £50,000 by 2020 . Labour says the plan amounts to a £7billion unfunded commitment .