Employers in England will be able to offer free rapid coronavirus tests to staff to take at home under the extension of a government scheme.
Home kits will be offered to firms with more than 10 employees from 6 April, where on-site testing is not possible.
Businesses should register by 12 April for the lateral flow tests, which can give results in less than 30 minutes, and they are free until 30 June.
Some 60,000 firms have already signed up for workplace testing.
The hope is that asymptomatic cases can be detected quickly, helping to prevent workplace outbreaks.
The wider availability of the rapid flow tests is part of government policy to ensure all kinds of workplaces are able to operate safely as lockdown measures are eased, with the stay-at-home rule ending on Monday.
The schools testing programme - in which pupils, their family members and staff at secondary schools and colleges are tested twice a week - combined with the wider use of workplace testing, has seen the total number of Covid tests carried out in the UK jump.
There were about 500,000 tests a day in mid-February - whereas on two days this week there were more than 1.8 million.
Initially, only businesses with 250 or more employees were eligible to access lateral flow tests. Earlier this month, it was made available to all businesses and this has now been extended to home testing.
Health Secretary Matt Hancock said rapid testing was a "vital part" of the roadmap out of lockdown, "helping us to cautiously lift restrictions on our economy and society".
"Around one in three people with coronavirus do not have any symptoms," he said. "So extending employee testing from the workplace to the home will help us identify more cases we otherwise wouldn't find, prevent further transmission and save lives."
Employees will be told to inform their bosses of a positive test result, as well as the NHS, which will then offer them a confirmatory PCR test.
British Retail Consortium chief executive Helen Dickinson welcomed the move, saying: "This is something we have called for as the next step for smaller businesses and stores where the space for testing at work is limited. It is also supported by employees as a practical approach."
Most businesses in England can register via an application form on the government's website. Charities and some other organisations, including those who are a building society, a partnership or a sole proprietor, will need to register by email, with details listed on the same web page.