As part of the announcement, the bank has said it will close branches in Lytham, Morecambe, Darwen, Nelson and Poulton in response to customers moving to mobile and online banking, which the bank has said is a long-term trend which has been accelerated by the coronavirus pandemic.
Santander said that the majority of the branches closing across the country are less than three miles from another Santander branch with the furthest distance being five miles.
The Lancashire branches will be closing in July and August.
Adam Bishop, Head of Branches, said: “Branch usage by customers has fallen considerably over recent years so we have made the difficult decision to consolidate our presence in areas where we have multiple branches relatively close together.
"The majority of the closing branches are within three miles of another branch and the furthest is five miles away.
“We will provide every support to customers of closing branches to find alternative ways to bank with us that best suit their individual needs.
"We are also working alongside our unions to support colleagues through these changes and to find alternative roles for those impacted wherever possible.
"We continue to believe that branches have an important role to play and we expect the size of our network to remain stable for the foreseeable future.
“We are committed to supporting our customers and responding to changes in the way customers want to access services."
Santander also said the branches closing in Lancashire are within half a mile of at least two free-to-use ATMs and one mile of the nearest Post Office.
The banks closing are:
Darwen - 10-11 Market Street, Darwen BB3 1DN 12 August 2021
Lytham Clifton Street - 75 Clifton Street, Lytham St Annes FY8 5ER 22 July 2021
Morecambe - 42 Euston Road, Morecambe LA4 5DD 5 August 2021
Nelson - The Centre, Nelson BB9 9SX 29 July 2021
Poulton - 18 Market Place, Poulton FY6 7AS 12 August 2021