On June 29th, 2016, the RIRs collectively signed the service level agreement (SLA) that has been negotiated with ICANN for the IANA services. This SLA or contract was negotiated as part of the number community’s portion of the IANA transition away from a US government contact with ICANN.
The IETF defines the Internet protocols and parameters, and in doing so delegates a portion of the number resources (IPv4, IPV6 & ASNs) used in those protocols to the RIRs for management.
The final step in the transition, from the numbering community’s perspective, is for the US government to allow the contact for the IANA services with ICANN to expire, sometime before Oct 1, 2017. Once the transition is completed, the RIRs will have a contract as a group with ICANN to provide the top-level coordination of the IPv4, IPv6, and ASN IP number resources.