73,000 arts and entertainment workers do not quality for statutory sick pay, according to trade union body TUC.
The figure amounts to one in eight sector workers, or 12% of the workforce.
TUC warns that tougher self-isolation rules introduced in light of the Omicron variant could leave these workers without income over the Christmas period.
“Our sick pay system is broken. No one should be left to choose between doing the right thing or putting food on the table," TUC General Secretary Francis O'Grady said.
The UK has the least generous statutory sick pay in Europe, the union says, worth £96.35 per week and only available to employees earning more than £120 per week.
The Government previously introduced a temporary scheme to assist people who face hardship if required to self-isolate, but TUC analysis found 64% of applications were rejected.