Gas and electricity supplier Co-operative Energy is offering to pay penalties for customers who switch from other companies, urging other firms to do the same.
The company said energy suppliers should waive exit penalties on fixed price tariffs so customers are free to switch and benefit from cheaper prices.
To back up the call, it has pledged to pay the exit penalties of the first 10,000 customers who switch to it.
The company, which is owned by its customers, has called for the end of the practice, which it claims locks customers into a fixed price contract then penalises them up to £100 if they decide to switch supplier.
Nigel Mason, from Co-operative Energy, said: "Thousands of customers were talked into signing fixed price contracts when energy prices were rising in the autumn.
"Now prices are falling and customers are checking the small print, they are facing punishing exit penalties making it impossible for them to switch to a lower tariff.
"It's a trap. These are tough times and people don't have money to waste so we're putting our hands in our pockets and offering to pay the exit penalties for any customer that switches out of a fixed price contract to Co-operative Energy.
"We think people should be free to switch supplier at any time. That keeps the supplier honest and ensures their prices remain competitive.
"Tying people in is a barrier to open competition. We need to be giving people a fair and honest deal, passing on price cuts as fast as we can and helping people manage their energy bills."
The offer is open to customers if they switch to Co-operative Energy. They must be leaving a fixed price contract and must supply proof of exit penalty after signing up, by email or post. The offer is limited to the first 10,000 customers who switch from a fixed term contract to Co-operative Energy.