Hunter United has about 10,000 members, assets worth $335 million and five local branches and IMB has more than 198,000 members, assets worth $6 billion and 48 east coast branches.

There will be no job losses in the merger - which was approved in a special meeting at Hunter United's Broadmeadow headquarters on March 5 and has received regulatory approval - and staff entitlements will be preserved.

Hunter United Employees' Credit Union Jann Gardner chair said its members and the broader community would benefit from its merger with customer-owned IMB Bank.

Ms Gardner said the merger would create more competition in the local banking sector, broaden Hunter United's offerings and expand its community support in the Hunter region.

"The merger will offer our members an expanded range of products and services while protecting our customer-owned way of banking," Ms Gardner said.

IMB Bank chair Noel Cornish, said the two organisations are a great fit with similar history, values and strong relationships with local communities adding that, like Hunter United, the Illawarra-based IMB had its history forged in steel.

Hunter United will continue to operate locally under its own brand from the merger date of April 1, 2020.