HarborOne Credit Union of Brockton, the second largest credit union in Massachusetts, is moving closer to becoming a bank.

Credit union members are slated to vote Monday on a proposal for HarborOne to become a mutual owned bank. The credit union board of directors ratified the plan last year.

HarborOne didn’t return calls seeking comment. But executives have previously argued the institution will have more flexibility as a bank, because it will be able to open branches in Boston (outside its traditional membership territory), serve a wider spectrum of customers, and make more commercial loans. Some members oppose the move, however, saying they don’t want to see their credit union turned into a bank. They argue that additional taxes and costs that banks must incur could mean higher lending and lower saving rates for members.

Advertisement - Continue Reading Below

HarborOne has 15 branches, $1.8 billion in assets, and 140,000 customers.