San Marino, on December 11, 2025, became the first jurisdiction to deposit its instrument of ratification for the Multilateral Convention to Facilitate the Implementation of the Pillar Two Subject to Tax Rule (the STTR Convention), the OECD said.
The STTR is a treaty-based rule that targets a defined set of cross-border intragroup payments. Where such payments are taxed below nine percent in the recipient’s jurisdiction, the rule allows the jurisdiction of source to apply additional tax up to that minimum rate. The Inclusive Framework on BEPS designed the STTR Convention so jurisdictions can implement the rule in existing bilateral tax treaties without negotiating bilateral amendments.
The STTR Convention will enter into force after a second instrument of ratification is deposited.