The UK competition watchdog has given five banks extra time to comply with so-called open banking plans aimed at boosting competition in retail banking.
This comes after the lenders said they would not be ready by a January deadline.
The Competition and Markets Authority (CMA) set out individual timelines today for Barclays, HSBC, Royal Bank of Scotland, Santander UK and Bank of Ireland to comply with the new rules after they said they would not be able to release all of the required data by the original January 13 deadline.
Each of the five banks was given a tailored plan with actions they must take to implement open banking with different deadlines set over the next year or so.
Britain's nine biggest banks are getting ready for open banking, which would involve sharing customers’ data with third parties that can then use it to build or recommend better suited products.
Under the new system, rivals can show a bank's customers how much they could save by switching lenders.
Financial technology, or fintech, companies are expected to offer smartphone apps and web sites that use customers' information to enable them to compare bank charges.
Banking data - dealing with matters as varied as account transactions, mortgage payments and fitness club subscriptions - are currently not easy to share with a third party in a format that computers can read for feeding into apps or for use by new banks getting off the ground.
The UK government wants to increase competition on the high street in a sector dominated by just five banks - HSBC, Barclays, Lloyds, RBS and Santander UK.
Under the original schedule, open banking for current accounts was due to begin on January 13, with a managed roll-out finishing in March 2018.