DENVER — EKS&H, a Denver-based accounting firm with major offices in Boulder and Fort Collins — is merging with Detroit-based Plante Moran.

Together, the two companies will form the 11th largest audit, tax, wealth-advisory and consulting firm in the United States.

The merger will be effective Oct. 1. Client service teams will remain the same, EKS&H said in a letter to its customers. Customer fees will also not be increased because of the transaction.

EKS&H has 38 employees at 1155 Canyon Blvd. in Boulder and 39 employees at 1321 Oakridge Drive in Fort Collins, according to BizWest research. It also has two offices in Denver and one in San Francisco. EKS&H was founded in 1978 and has grown to 70 partners and 700 team members. There are 300 CPAs companywide.

Plante Moran has 2,200 employees in Michigan, Ohio and Illinois, as well as Shanghai, Tokyo, Monterrey and Mumbai. The company has 22 offices.

“Our firms share a commitment of offering a dedicated and differentiated client experience by focusing on our clients and our staff,” EKS&H founder partner and CEO Bob Hottman said in the client letter.

Hottman said that clients will have “greater access to industry and technical expertise and new service offerings,” including “greater depth and capabilities around international audit, tax, and consulting services.”