Postby someone » Fri Jun 25, 2021 7:33 am
It's almost certainly dependent on the bank but it's almost guaranteed that they won't keep records going back more than seven years.
Keeping data has a cost and, worse, answering things like FOI requests gets more and more complicated the more old data you have to be prepared to search.
I'd guess that in almost all cases banks will delete/destroy old data as soon as they are legally allowed to. It's much easier to say "We don't keep data that old" rather than "sorry, we'll have to send someone down the mine to search through all the old tapes to see if we can find some going back that far, then we'll have to extract them and have someone search through the data for your data and we might not find anything anyway"
(I'm not exaggerating, one place I worked at really did store their older backup tapes at a disused mine, I think it was a salt mine but it was so long ago now that I might be misremembering)
At least one of my banks keeps my entire last five (seven?) years of banking history available online. I'd be surprised if they keep any more offline.