A current account usually gets defaulted a year later - no earlier than the OD annual review.
Example. You apply for an OD in March. Every March they review it and reduce or increase or leave the same. On occasion they remove it and demand immediate repayment. However lets assume you stop using the account in April (year irrelevant); the bank can at their leisure do any of, any combination of, all of or none of those actions.
Usually they'll let it go till the review (following March / 11mths) and they'd then remove the facility as you breached terms (by not using account) and they'll start recording [1]'s to [6]'s afterwhich they'll default you. So that'll usually be around 19 months AFTER you last used the account.
However if you exceed the agreed OD then they'll record 1's to 6's pretty much after a month (in our example it'd be May/June) and keep a trailing [6] right through till the review the following March before agreeing to leave the OD in place or removing it before defaulting you. If they leave it, you'll get another year of [6]'s before they default it.
My hsbc has 3 years of [6]'s. I'll argue when I'm sure it's SB'd

Questions?
Leave a comment: