The Lawn Tennis Association is planning to stage all the major grass-court tournaments this summer, but says the cost will double due to Covid-19.
Events at the Queen's Club and in Eastbourne could take place behind closed doors, if necessary, but the governing body is "cautiously optimistic" fans will be present.
None of the grass-court tournaments were staged in 2020 because of the pandemic, with Wimbledon cancelled for the first time since World War Two.
"Our hope right now is that we will have some level of spectator attendance at all our events," said the LTA's chief executive Scott Lloyd.
"We know how much fans want to come back, and the sport isn't the same without them, so we are planning for their return and hoping that circumstances will make that possible."
Creating Covid-secure venues, and booking suitable hotel rooms, will drive up the cost.
As a result, the lower tier tournaments in Ilkley have been moved to Nottingham, and the events in Surbiton and Manchester have been cancelled altogether.
This will heighten the difficulties of lower ranked professionals, who are already finding playing opportunities hard to come by. The LTA says it is committed to staging more in the way of domestic events in the years ahead.