State regulators have fined Frontier Communications $41,400 for 414 violations of Washington’s law governing the largest amount a company can charge for a returned check.

The Washington Utilities and Transportation Commission gave Frontier 15 days to pay the fine, contest it by requesting a hearing, or seek a reduced penalty settlement.

The state found Frontier guilty of charging customers $20-25 for returned checks from Aug. 1, 2010 – March 31, 2012, despite the fact the maximum penalty Frontier is authorized to levy for a returned check in the state is $15.

Customers who overpaid Frontier for returned check charges should contact Frontier at 1-800-921-8101 to negotiate a partial refund or service credit. The state’s fine will not be used to repay customers.