There is no fixed schedule that applies to every merchant. Your verification has an expiry date, and we also review accounts when something changes — for example your business model, ownership, or the volumes you process.
When an update is needed, we will contact you and tell you exactly what is required and by when. You do not need to send anything in advance.
For a fuller explanation of these periodic reviews, see Why is CoinGate asking me for documents again? (Ongoing Due Diligence).