The back-end service provider for the .rio TLD has implemented some operational changes. As a consequence, registrant changes are now possible.
That means you can replace the registrant contact of a .rio domain with a new contact. Although this transaction is immediately processed if all policy requirements are met, the new registrant is subject to verification with the tax authorities. If the taxpayer ID of the new registrant is not in good standing, the domain will be put into ServerHold status.