The report by Royal London, seen by the BBC, found that 5.2 million workers have turned to second or multiple jobs to help pay for the increased cost of living, while another 10 million plan to.
It found that 16% of workers in the UK have taken on an additional job to help pay for the cost of living increases, while another 30% will need to do so if costs continue to rise.
For many UK employees, working more hours is not a realistic option. Over a quarter of the full-time employees are already working over 48 hours a week, according to the research.
Many people are still finding it hard to bring in enough money to cover bills despite working long hours or multiple jobs. Nearly a third of people are already having to spend money they don't have, borrowing or using their bank overdraft, according to the research.
It could be an incredibly tough winter ahead, as many households started reining in spending six months ago, as costs started to rise, but with bills continuing to climb, it could be an incredibly tough winter ahead, said Sarah Pennells, consumer finance specialist at Royal London.
While many have resorted to making significant spending adjustments, others just can't keep their heads above water, despite working all the hours they can. The government's energy price freeze announcement will have brought relief, but escalating costs are deeply worrying, with only one in ten adults confident that they'll be able to cope financially, she said.