Other parts of the plan include a reduction in tax rates, including cutting the top rate from 39% to 33%, an increase in the child tax allowance, and a restoration of the married couples allowance.
BBC: $1,350bn US tax cut deal
2.
Explaining his plans for a married couples allowance, shadow chancellor George Osborne told the Times the policy was about "supporting commitment".
BBC: David Cameron with wife Samantha
3.
Mr Portillo also pledged to cut taxes on businesses, to restore the married couples allowance, to give more help to pensioners - and to cut the duty on petrol.