Up to three households will be able to meet up during a five-day Christmas period of 23 to 27 December, leaders of the four UK nations have agreed.
People can mix in homes, places of worship and outdoor spaces, and travel restrictions will also be eased.
But a formed “Christmas bubble” must be “exclusive” and would not be able to visit pubs or restaurants together.
The leaders urged people to “think carefully about what they do” to keep the risk of increased transmission low.
They added 2020 “cannot be a normal Christmas” but family and friends will be able to see each other in a “limited and cautious” way.
Anyone travelling to or from Northern Ireland may travel on the 22 and 28 December, but otherwise travel to and from bubbles should be done between the 23 and 27, BBC reported.
People will not be able to get together with others from more than two other households, and once a bubble is formed, it must not be changed or be extended further.
The guidance says a bubble of three households would be able to stay overnight at each other’s home but would not be able to visit hospitality, theatres or retail settings.