The Additional Protocol is a legal instrument that modifies a safeguards agreement with the International Atomic Energy Agency (IAEA) and gives the IAEA additional tools to address undeclared activities in the state as a whole. The IAEA Board of Governors approved by the Model Additional Protocol, published as INFCIRC/540, in 1997. Under an Additional Protocol, the State is required to provide additional declarations and access to the IAEA. As of 31 May 2015, 147 countries had an Additional Protocol approved by the IAEA Board of Governors, 146 countries have signed, and 125 countries brought it into force.
- Model Protocol Additional to the Agreement(s) between the State(s) and the International Atomic Energy Agency for the Application of Safeguards, INFCIRC/540 (Corrected).
- "IAEA Safeguards Overview: Comprehensive Safeguards Agreements and Additional Protocols". https://www.iaea.org. Retrieved 31 May 2015.
- "Conclusion of safeguards agreements, additional protocols and small quantities protocols" (PDF). Retrieved 31 May 2015.
- "Conclusion of Additional Protocols: Status as of 14 May 2015" (PDF). Retrieved 31 May 2015.