Decisions on whether the government will help people buy equipment to receive digital TV have yet to be made, says Culture Secretary Tessa Jowell.
Ms Jowell says decisions will now be taken "rapidly"
It hopes the analogue switch off will begin in 2008, but there are concerns many viewers will not be prepared.
Ms Jowell told BBC One's Breakfast With Frost it was "unthinkable" that anybody would be left unable to watch TV after the switchover.
She said the vulnerable and poor were of primary concern in any plans.
"We are not at the point yet of making decisions about whether we need to give free set-top boxes," she said.
"Those decisions will be taken, but they are decisions for three or four years' time, not now."
She said the price of set-top boxes which enable digital television to be received had fallen drastically.
Ms Jowell expressed her concern that everyone should be aware of what was happening with the switch off of the analogue signal.
"I expect decisions to move quite rapidly between now and the end of the year on the exact timing and the phasing," she said.
"There won't be a national switchover day. What will happen is that regions will switch one at a time.
"All the undertakings have to be to ensure a very clear transition for people, and very particularly elderly people, vulnerable people, people who may find it hard to cope with new technology.
"We've got to make sure that before we press the button, their interests are looked after."
Media regulator Ofcom had recommended that the switchover begins in the Wales, the West Country and the northern counties of England in 2008.
London and the South East would be the last to receive digital only television in 2011.