| Abbreviation | Definition |
|---|---|
| IPT | Insurance Premium Tax (UK) |
| IPTS | Integrated Property Tax System |
| IRAs | Individual retirement arrangements |
| IRTP | Internal Revenue Tax Paid |
| ISTD | Income and Sales Tax Department |
| ISTS | Industry Sales Tax Solutions |
| IT | Inflation Tax |
| IT | Inheritance Tax |
| ITA | Interactive Tax Assistant |
| ITAT | Income Tax Appellate Tribunal |
| ITAX | Income Tax |
| ITBR | Income Tax Board of Review |
| ITCE | Input Tax Credit Entitlement |
| ITCI | International Tax Competitiveness Index |
| ITDF | International Tax Directors Forum |
| ITDR | International Tax Disputes Resolution |
| ITH | Indirect Tax Hub |
| ITIA | Illinois Tax Increment Association |
| ITIC | International Tax and Investment Center |
| ITIG | Immigrant Tax Inquiry Group |