The operator of British cruise lines P&O Cruises and Cunard is planning to make hundreds of staff redundant.
It is thought 450 jobs could go at Carnival UK's headquarters in Southampton, where about 1,600 people currently work.
Staff who keep their jobs are being asked to accept a 20% pay cut until November.
Last month it announced sailings were suspended until at least 31 July due to the coronavirus pandemic.
In a statement, Carnival said: "Unfortunately like many businesses, Covid-19 has continued to impact our way of life.
"It is necessary to make changes to our organisation to build a stable platform for the time we phase our ships back into service and for future growth."
A Carnival spokesman confirmed it had begun consulting staff based at its headquarters Carnival House in Harbour Parade.
By Paul Clifton, BBC South transport correspondent
Carnival is by far the world's biggest cruise company. It is by far the biggest operator in Southampton, which is the busiest cruise port in northern Europe.
The 450 posts at risk are shore staff, mostly office jobs.
The company has already sent home all the ships' crew it can, and that will come to a far larger number. On many ships, there are 50 or 60 different nationalities on board.
During this crisis many travel businesses have been severely cut back. But the cruise industry has been wiped out.
No cruise ships are operating anywhere in the world. And in the UK, this is a business that - in normal times - supports more than 60,000 other jobs. They are at risk too.