The switch to online banking has seen branch footfall in those sites drop by over half, it said.
Cost-cutting in the banking sector has led to the closure of thousands of branches in recent years.
In July, Lloyds Banking Group said it would close 66 branches between October 2022 and January 2023.
In its latest announcement, the group said Halifax will close 18 sites, while Lloyds will shut 22 between April and June.
All but one of the closures are in England, with Halifax closing its site in Bangor, Wales.
The group said there were no job losses as a result of the closures.
The number of people using services in-person has been falling for years as more people do their banking online.
The group said the branches to be closed have seen the number of visits drop dramatically in the last five years.
“Branches play an important part in our strategy but we need to have them in the right places, where they are well-used,” a group spokesperson said.
They added that all of the branches due to close have at least one free-to-use cash machine or a Post Office within a third of a mile.
The Halifax branches shutting are in: Bangor, Chester-le-St, Fenchurch Street in London, Aldershot, Chorlton-cum-Hardy, Crouch End, Golders Green, Putney, Norbury, Surbiton, Chingford Mount, Redruth, Bletchley, Maldon, St Neots, Whitley Bay, Grays and Purley.