Arts union Equity has written to the chancellor and culture secretary to say most of its members are still "in serious need of financial help".
Government schemes so far have proved "inadequate and patchy at best", its general secretary and president said.
"Creative workers need action now," they wrote, adding that many were "struggling to stay afloat".
A government spokesperson pointed to its "generous" support including the the £1.57bn Culture Recovery Fund.
In their letter, Paul W Fleming and Maureen Beattie wrote: "The reality for most of our members, including thousands of people who regularly work throughout the community in care homes or delivering theatre in education, is that there is no route back to work any time soon.
"With this crisis certain to last for months to come, our members will soon pass the year's mark since our industry's closure - a year without regular, reliable income for the vast majority of our membership."
Equity represents actors and other "creative practitioners". Four out of 10 could not access the Self-Employed Income Support Scheme (SEISS), Equity said.
It added that freelancers in Scotland, Wales and Northern Ireland had received some additional support, but "those in England have not received any further help".
In response, the government spokesperson said the SEISS was "one of the most generous in the world" and that it had "provided billions in support to the UK's world-class cultural sector", including the Culture Recovery Fund and the £500m film and TV insurance scheme.
"At the upcoming Budget we'll outline the next stages of our Plan for Jobs to support businesses and families across the UK," they added.
In July, Equity welcomed the support from the Culture Recovery Fund Equity but its previous general secretary, Christine Payne, said it was important that the funding didn't just prop up venues.
Meanwhile, Manchester City Council has decided to launch its own hardship fund for arts freelancers in the city, using £500,000 from retailer B&M and The Savannah Wisdom Foundation.
"Manchester's arts and culture sector contribute massively to city life and to its economy and have an important part to play in the city's recovery from the pandemic," councillor Luthfur Rahman said.
"We're fully committed to continuing to do everything we can to support it now and in the future."
According to the latest figures from the Office for National Statistics, three-quarters of arts, entertainment and recreation businesses said their turnovers in the second half of December were lower than usual - the joint highest of any sector, along with accommodation and food services.
And half of arts, entertainment and recreation staff were on furlough - more than for any other industry.
A European study has found that the continent's cultural and creative sector has been hit harder by the coronavirus crisis than every other industry except aviation, according to The Guardian.
The sector's revenues dropped by 31.2% last year compared with 2019, just behind aviation on 31.4%, the paper said, citing a report by the European Grouping of Societies of Authors and Composers (GESAC).