Mauritius Protocol Ratification Gives Indian Tax Officials Power to Probe Offshore Investor Structures

What the Mauritius Protocol Ratification Changes for Offshore Investing

The Mauritius cabinet has ratified a 2024 protocol amending the double taxation avoidance agreement (DTAA) with India, a move that will hand Indian income-tax officials a powerful new tool to challenge offshore investment structures. At the heart of the protocol is the Principal Purpose Test (PPT), an OECD-aligned rule that allows treaty benefits—such as capital gains exemptions and reduced dividend tax rates—to be denied if one of the principal purposes of the arrangement is to obtain a tax advantage.

Until now, Indian authorities could only contest Mauritius treaty claims by invoking domestic General Anti-avoidance Rules (GAAR) or relying on judicial anti-abuse doctrines, both of which required proving the entity was a sham or that the whole structure lacked commercial substance. The PPT lowers that bar: even a Mauritius entity with “operational substance” can be denied benefits if a tax officer determines that tax avoidance was a main driver of the investment.

The ratification follows a January 2026 Supreme Court ruling in the Tiger Global case that cast doubt on whether a simple tax residency certificate from Mauritius was enough to secure treaty relief. Combined with that verdict, the protocol signals a clear shift from India’s revenue authority toward substance-based enforcement and gives frontline assessing officers direct authority to apply the PPT, without the need for a high-level panel’s sign-off as required under GAAR.

Once India completes its own ratification process, the protocol will apply prospectively but, crucially, its language suggests it could reach investments made on or after 1 April 2017—not just those made after the protocol’s entry into force. This has raised urgent questions about the tax certainty of legacy offshore structures, especially for private equity and venture capital funds that have long relied on Mauritius as a gateway into India.

How the PPT Reshapes Treaty Benefits and Investor Scrutiny

Lowering the Bar for Tax Challenges

The biggest change is procedural. Under GAAR, a tax officer’s proposal to deny treaty benefits must go through a high-level statutory panel, a safeguard that often delayed and diluted enforcement. The PPT, by contrast, is embedded in the treaty itself and can be invoked directly by the assessing officer. That shifts the burden to the investor, who will need to proactively demonstrate that tax was not a principal purpose of the structure—a far more subjective and searching inquiry than merely showing a certificate of tax residency.

Impact on Pre-2017 and Post-2017 Investments

Grandfathering provisions protect shares bought before 1 April 2017 from capital gains tax, and the Central Board of Direct Taxes (CBDT) has clarified in Circular No. 1/2025 that the PPT will not disturb those protections. However, investments made after that date but before the protocol’s entry into force face genuine uncertainty. The protocol text states the PPT applies “irrespective of the taxable years to which the relevant taxes relate,” which legal experts, including Ashish Karundia, interpret as reaching back to transactions from 1 April 2017. For the large pool of private equity and FPI structures set up between 2017 and 2024, this retroactive potential could trigger fresh tax demands.

What Counts as Substance After Tiger Global

The Protocol’s emphasis on “genuine commercial substance” echoes the Supreme Court’s stance in the Tiger Global matter, where the court questioned whether a tax residency certificate alone was sufficient. Now, investors must be prepared to show that their Mauritius entities are not merely conduits but have real decision-making, office space, employees, and operational risks. The PPT adds a motives test, meaning even a well-staffed substance entity could be challenged if the investment’s design was primarily tax-driven. Law firms like Khaitan & Co have called for detailed implementation guidance on what evidence will satisfy an assessing officer, otherwise the risk of arbitrary denial increases sharply.

Winners and Losers

The main beneficiaries are the Indian tax authorities, who gain a more agile enforcement tool, and, potentially, domestic investors who have long argued the Mauritius route gave foreign funds an unfair tax advantage. The clear losers are foreign portfolio investors and private equity funds that structured through Mauritius without building deep substance, as well as the island’s financial services sector, which faces a reduction in treaty-driven capital flows. Those who can afford to restructure and build genuine local operations may weather the change, but the cost and time involved will disadvantage smaller funds.

Immediate Steps for Investors and Advisers After the Protocol

• Audit Mauritius structures created after 1 April 2017. Map every investment vehicle and identify which ones lack significant people functions, office presence, and board decision-making in Mauritius. These will be the easiest targets for a PPT challenge.
• Prepare substance documentation immediately. Tax officers will look for board minutes held in Mauritius, local employment contracts, operational bank accounts, and evidence that key decisions are not being made elsewhere. Start building that evidence trail now, even before the protocol comes into force.
• Review the tax motivations behind existing structures. Any written communication—internal memos, fund marketing materials, investment committee notes—that mentions tax efficiency as a driver could be cited under the PPT’s motive test. Privileged or not, those documents will matter in litigation.
• Engage with the CBDT’s forthcoming implementation guidance. The government has promised further clarification on how the PPT will be applied to legacy structures. Directly or through trade bodies, submit comments that request bright-line tests for acceptable substance levels and a clear timeline for the treatment of investments between 2017 and 2024.
• Consider restructuring now, not later. Moving key functions to Mauritius, appointing local independent directors, and transferring economic risk to the island may become necessary. Delaying until the first PPT notices arrive will be far costlier than proactive restructuring.