Students in England will be urged to take two Covid tests three days apart, to cut the risk of spreading infection when they travel home for Christmas.
These are lateral flow tests with rapid results - with those testing negative expected to leave university within the following 24 hours, according to the latest guidelines seen by the BBC.
The pre-Christmas testing will start in many universities early next week.
But testing will remain voluntary - and not all universities will offer tests.
The National Union of Students said there should be capacity for all students who wanted a test to get one before Christmas.
More than a million students in England will leave their university addresses to spend the Christmas holidays in another part of the country - and plans for testing are intended to stop this migration from spreading coronavirus.
It is understood that most universities, but not all, are taking part in the government's plans for the mass testing of students using lateral flow tests, starting on 30 November.
Durham University, which has piloted testing, says about 2,000 students have already booked tests ahead of the Christmas departures.
The government guidelines recommend a double test to increase accuracy, three days apart, in the form of swab tests administered by the students themselves, at centres being set up by universities.
The results will be sent by text or email - with students who are not infected expected to leave their term-time accommodation "immediately", which is defined as within 24 hours of the second negative test.
Getting students to leave soon after they get results is intended to cut the risk of infections post-testing.
"The closer to your travel time the better," says Professor Jacqui Ramagge, who is leading on testing for Durham University. And at her university, the two tests will be seven days apart rather than three.
Ministers are urging students to take Covid tests before travelling, as a way of protecting their families, but it is not compulsory and not all universities will offer the testing.
Those who do not take tests, or only have one test, will still be able to leave at the same time - with an encouragement to "travel home as safely as possible" during the "travel window" of 3 to 9 December, which the government has identified as when it expects most students to leave university for Christmas.
This will be after the current lockdown ends on 2 December, and ahead of universities switching to online teaching for the end of term.
Students who test positive will be directed towards taking another type of test - a PCR (polymerase chain reaction) test to confirm whether they are infected - and will have to stay and self-isolate while waiting for the result.
But those who test positive from this PCR test will be required to stay in their term-time accommodation for 10 days of self-isolation - which should still leave enough time to get back before Christmas.
Teesside University is among those opening testing centres from 30 November - and is encouraging students to book for two lateral flow tests at its Middlesbrough campus.
Pro Vice-Chancellor Professor Mark Simpson said it would provide a "quick and easy testing option to our students and enable them to make an informed decision about returning home for the upcoming Christmas break".
He said it would help to address the "considerable anxiety and a need for reassurance" about the safety of travel ahead of the end of term.
Universities Minister Michelle Donelan said: "Testing will offer further assurances that students can keep their families safe this winter, and I urge all students who can to take the tests on offer."