A savings account becomes 'dormant' after two years in which its owner makes no transaction himself: no withdrawal, deposit, transfer, or even a balance inquiry. Entries the bank makes on its own, such as crediting interest or debiting fees, do not count as activity.
If the account becomes dormant:
Interest does not stop; it keeps accruing on an account that earns a return.
Standing orders and cheques keep executing.
The bank must notify you beforehand and tell you about any charges and how to reactivate.
Reactivation: if you have another active account at the same bank, you can reactivate through any of the bank's channels after an identity check. If all your accounts there are dormant, you will need at least a balance confirmation and a written request. The rules bar the bank from charging for reactivation or closure.
These rules apply to accounts, not to deposits or certificates. If you are unsure of your account's status, ask the bank or check your latest statement.