A loophole that allows viewers to catch up on TV shows on the BBC iPlayer for free will close in September.
People will risk prosecution and a £1,000 fine if they download or watch shows on iPlayer without a TV licence on any device.
However, it is unclear how the new rules will be enforced, as there are no plans to ask viewers to enter their licence fee details on iPlayer.
Currently, only live content is covered by the £145.50-a-year licence fee.
Last year, the BBC announced a £150 million shortfall in licence fee income for 2016/17, saying there had been a faster-than-predicted fall in the percentage of households owning televisions because of people viewing through catch-up.
The Government committed to closing the loophole, with John Whittingdale, then culture secretary, stating in March: "The BBC works on the basis that all who watch it pay for it.
"Giving a free ride to those who enjoy Sherlock or Bake Off an hour, a day or a week after they are broadcast was never intended and is wrong."
The Government set out plans to update licence fee legislation, as part of negotiations which saw the corporation agreeing to cover the cost of providing free licences for over-75s.
People who already have a TV licence will not be affected by the change.
A TV Licensing spokesman said: "At present there are no plans to make people enter their licence fee number but we are looking at all options.
"As of 1 September 2016, a change in the law means you need to be covered by a TV licence to download or watch BBC programmes on demand - including catch-up TV - on BBC iPlayer.
"This applies to all devices. The change will not affect the huge majority of households which are already licensed."