NCUA-insured credit union
Mass Bay — South Boston, MA
Credit Union headquartered in South Boston, Massachusetts.
Source: NCUA call report data, data as of March 31, 2026, fetched September 5, 2026
Headquarters and contact
| Address | 147 W 4Th St South Boston, MA 02127 |
| County | Suffolk |
| Website | not published in NCUA data |
| Phone | (617) 269-2700 |
NCUA record
| NCUA Charter | 68137 |
| Federal Reserve RSSD ID | 22196 |
| Status | Active |
| Charter type | 2 (STATE) |
| Financials as of | March 31, 2026 |
How to find your Mass Bay routing number
NCUA does not publish ABA routing numbers, and many credit unions use different routing numbers by state or by account type. The reliable places to find yours: the bottom left of a check from this credit union, the "account details" screen in its online banking, or its official website.
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Offices
| South Boston main office South Boston, MA |
147 W 4Th St, 02127 (617) 269-2700 8:45 AM to 4:15 PM |
| Everett Everett, MA |
183 Main St, 02149 (617) 269-2700 8:45am-4:15pm |
| Quincy Center Quincy, MA |
1250 Hancock St, 02169 (617) 269-2700 8:45 AM to 4:15 PM |
| Seaport Branch South Boston, MA |
409 D Street, 02127 (617) 269-2700 8:45 to 4:15 M-W, F8:45 to 6:00 Th |
Where Mass Bay has offices
Cities with the most Mass Bay offices
Other credit unions headquartered in South Boston
| City of Boston | $546.18 million |
| Taupa Lithuanian | $29.58 million |
Largest credit unions headquartered elsewhere in Massachusetts
| Rockland Rockland | $3.74 billion |
| Metro Chelsea | $3.30 billion |
| Workers Littleton | $2.51 billion |
| Brightbridge Lawrence | $2.39 billion |
| Hanscom Hanscom AFB | $2.19 billion |
| Jeanne D'arc Lowell | $2.19 billion |
| Greylock Pittsfield | $1.71 billion |
| Webster First Worcester | $1.50 billion |
Compare before you open an account: today's CD and savings rates, the CD calculator and the savings calculator.
