The Post Office is desperately trying to encourage more banks to provide current account services at its branches.
By the end of this year, Natwest and Royal Bank of Scotland (RBS) customers are likely to finally have access but millions of other account holders will still be denied, including most HSBC and Santander customers.
Most consumers with a basic bank account can access their account balance at the Post Office and deposit and withdraw money, but many standard current account holders are not able to do the same.
Such services can often prove a lifeline for those in rural communities where their nearest bank branch can be miles away.
A Post Office spokeswoman says: "The Post Office regularly talks to the major banks, for which arrangements are not in place, to promote the services and are working towards a position where all UK current account holders can use the Post Office."
MoneySavingExpert.com understands the Government is concerned at the failure of some banks to offer Post Office services. Ultimately, the decision is down to providers.
Basic bank accounts are those without an overdraft facility, designed for those with a poorer credit rating.
What Post Office services do providers offer?
As the table below shows, HSBC, RBS/Natwest and Santander (other than former Alliance & Leicester (A&L) customers) have no access to a standard current account at a Post Office, while the trio also limit services for basic account holders.
All other major banks and building societies offer either all or most of the available facilities at a Post Office.
But only Bank of Ireland, Clydesdale, Halifax, Lloyds TSB and The Co-op offer the full range of available services.
Customers with Bank of Ireland, Barclays, Cahoot and Lloyds TSB can also cash personal cheques.
Services at Post Office
|Standard account||Basic account|
|B. of Ireland||Yes||Yes||Yes||Yes||Yes||Yes|
|B. of Scot||Yes||Yes||No||Yes||Yes||No|
Source: Post Office. A&L merged with Santander last year.
Will more providers offer current accounts at the Post Office?
Of those that do not offer any service for standard account holders, neither HSBC nor Santander have any plans to offer Post Office-based banking at present.
An HSBC spokesman says: "We have 1,300 branches across the UK and the vast majority of our customers live a reasonable distance from a branch.
"Plus there are lots of other options for banking such as online or over the phone."
A Santander spokesman says: "We have no plans to offer services at the Post Office but we are are constantly reviewing the services we offer customers."
In contrast, RBS/Natwest has confirmed it is considering providing current accounts at the Post Office at some point this year.
A spokeswoman says: "Meetings have been held to progress the detailed arrangements between RBS and the Post Office.
"We hope to produce a delivery timeline by the end of April once the design stage of the IT programme has been completed."
While Post Office services can provide vital access to banking in rural areas where banks no longer have a presence, the number of Post Office branches has fallen over recent years.
Some 2,500 closed down between 2005 and October 2010. There are about 12,000 Post Office branches, more than all high street banks combined.
Further reading/Key links
Cut debt costs: Best Bank Accounts, Top Savings Accounts, Basic Bank Accounts
Get debt help: Debt Problems