When is tax on savings interest paid?

Krakkkers

Lets say i have £66500 invested at 5% interest fixed for 5 years paid monthly into the same account.
After 5 years it will be worth £85,000 but when will the tax be paid? When the account matures? Yearly?
Assume i pay basic rate tax and have used my tax free savings allowance.

Albermarle

The question is asked regularly and there seems to be not a definitive answer in all cases . See this link and eskbankers post.
When to pay tax on interest for multi-year savings accounts? — MoneySavingExpert Forum