| Abbreviation | Definition |
|---|---|
| IATT | Interim Authority to Test This |
| IBA | Israel Broadcasting Authority |
| IBTA | Interdimensional Bridge And Toll Authority |
| ICC | International Code Council |
| ICFA | Independent Cities Finance Authority |
| ICRA | International Cultivar Registration Authorities |
| ICRA | International Cultivar Registration Authority |
| ICTA | Information and Communication Technologies Authority |
| IDAL | Investment and Development Authority of Lebanon |
| IDRA | Insurance Development and Regulatory Authority |
| IDWA | Illawarra District Weeds Authority |
| IFCA | Inshore Fisheries and Conservation Authorities |
| ILEA | Inner London Education Authority |
| IMDA | Infocommunications Media Development Authority |
| IPOA | Incompetent Police Oversight Authority |
| IPOA | Independent Policing Oversight Authority |
| IRAI | Insurance Regulatory Authority of India |
| IRDA | Indian Regulatory Development Authority |
| ISA | Independent Safeguarding Authority |
| ISCAP | Issue Severity Capabilities Authority And Plan |