The OSB Group includes the following limited companies registered in England and Wales:
| Company Name | Registered Number | Registered Office | Trading Names |
| OSB GROUP PLC | 11976839 | OSB House, Quayside, Chatham Maritime, Chatham, Kent, United Kingdom, ME4 4QZ | |
| OneSavings Bank plc | 07312896 | Reliance House, Sun Pier, Chatham, Kent, ME4 4ET | Krbs Kent Reliance Kent Reliance Banking Services Reliance Property Loans Rely Mortgages |
| 5D Finance Limited | 05694526 | The Observatory, Brunel Way, Dock Road, Chatham, Kent, United Kingdom, ME4 4AF | |
| Easioption Limited | 04508404 | The Observatory, Brunel Way, Dock Road, Chatham, Kent, United Kingdom, ME4 4AF | |
| Guernsey Home Loans Limited | 04508403 | Reliance House, Sun Pier, Chatham, Kent, ME4 4ET | |
| Heritable Development Finance Limited | 08606584 | The Observatory, Brunel Way, Dock Road, Chatham, Kent, ME4 4AF | |
| Inter Bay Financial Limited | 05878146 | OSB House, Quayside, Chatham Maritime, Chatham, Kent, United Kingdom, ME4 4QZ | |
| InterBay Asset Finance Limited | 05929676 | Reliance House, Sun Pier, Chatham, Kent, ME4 4ET | |
| Interbay Funding, Ltd | 05595882 | Reliance House, Sun Pier, Chatham, Kent, ME4 4ET | InterBay Commercial |
| Interbay ML, Ltd | 06038070 | OSB House, Quayside, Chatham Maritime, Chatham, Kent, United Kingdom, ME4 4QZ | |
| Jersey Home Loans Limited | 04508389 | Reliance House, Sun Pier, Chatham, Kent, ME4 4ET | |
| Prestige Finance Limited | 01080632 | Reliance House, Sun Pier, Chatham, Kent, ME4 4ET | |
| Reliance Property Loans Limited | 04508405 | Reliance House, Sun Pier, Chatham, Kent, ME4 4ET | |
| Rochester Mortgages Limited | 09928431 | The Observatory, Brunel Way, Dock Road, Chatham, Kent, ME4 4AF | |
| CCFSG Holdings Limited | 06712054 | OSB House, Quayside, Chatham Maritime, Chatham, Kent, United Kingdom, ME4 4QZ | |
| Charter Court Financial Services Limited | 06749498 | 2 Charter Court, Broadlands, Wolverhampton WV10 6TD | Charter Savings Bank Precise Mortgages Exact Mortgage Experts |
| Exact Mortgage Experts Limited | 06749563 | 2 Charter Court, Broadlands, Wolverhampton WV10 6TD | |
| Charter Mortgages Limited | 06749495 | 2 Charter Court, Broadlands, Wolverhampton WV10 6TD | |
| Broadlands Finance Limited | 06957973 | OSB House, Quayside, Chatham Maritime, Chatham, Kent, United Kingdom, ME4 4QZ |
The VAT Registration Number for all the above companies in the OSB Group is 823 8508 22.