Basic bank account holders at Barclays face more frequent charges if they fail to have sufficient funds in their accounts.
Basic accounts, often opened by those with a chequered credit history, do not offer cheque books or overdrafts.
At present, there is a maximum charge of £8 a day if direct debit or standing order payments exceed the total funds in the account.
However, from March, this could increase to up to £24 a day.
That is because a limit of just one transaction charge occurs at present, but this will be extended to charges for each of up to three missed payments in a day.
Barclays' move follows changes made by other High Street banks to cash machine access for customers with basic bank accounts.
Basic bank account customers at RBS and Lloyds Banking Group - which includes Halifax and Bank of Scotland - are being restricted in the number of cash machines they can use.
The banks blamed high costs for the changes.
Those with basic bank accounts with Barclays will not have the same restrictions on ATMs. Instead, the bank has decided to cut costs by increasing the frequency of charges.
It will also save money by a default option of only sending out paper statements once every three months, rather than monthly, although customers can ask for a statement each month if they would like it.
However, a £2 a month charge for a text service to alert account holders that they are close to emptying their funds has been cancelled. The service is now available free.
Watchdog Consumer Focus is critical of all of the three banks' changes to basic banking which it says discourages the poorest and most vulnerable from using bank accounts.
"These changes to basic bank accounts are a backward step by banks which could increase financial exclusion," said Oliver Morgans, of Consumer Focus.
"Living without a bank account can make it hard to live in the 21st century and can create financial penalties for the households who can least afford it.
"The government already faces an uphill struggle to persuade customers to sign up to a bank account when many people distrust banks and the charges they make. These changes will make that hill even harder to climb."
However, a Barclays spokesman said: "We want to ensure this product remains financially sustainable so that we can continue to help those at risk of financial exclusion gain access to banking.
"We also want to ensure the product continues to meet the needs of those it is designed for. The changes we are making are based on solid research of our customer base and Citizens Advice Bureau clients."