Green bonds vs sustainability-linked bonds in India

Green bonds vs sustainability-linked bonds is the most consequential distinction in India's sustainable finance rulebook, because the two instruments make opposite promises. A green bond promises that the money will fund a defined kind of project and nothing else. A sustainability-linked bond promises nothing about the money at all; it promises that the bond's own terms will change if the issuer misses its targets. Both are ESG debt securities under the same regulation. This comparison sets out where each rule bites. It is not investment advice.

Green bonds vs sustainability-linked bonds compared

Where the money goes, or what the numbers do

The mechanical difference decides everything else about the two rulebooks.

A green debt security is a use-of-proceeds instrument. Regulation 2(1)(q) lists thirteen project categories, and the security qualifies only if the proceeds fund one of them: renewable and sustainable energy, clean transportation, climate change adaptation, energy efficiency, sustainable waste management, sustainable land use, biodiversity conservation, pollution prevention and control, circular economy products, blue bonds, yellow bonds, transition bonds, and any further category SEBI specifies. Because the promise is about destination, the disclosures are about tracking. The offer document describes the system used to trace deployment, and the annual disclosures report utilisation verified by an external auditor, unutilised proceeds separately for each ISIN, the project list with amounts disbursed, and impact project by project. The detail is in what are green debt securities.

A sustainability-linked bond has no destination test. Its definition turns on the bond's financial or structural characteristics being linked to predefined sustainability objectives, measured through predefined Sustainability Key Performance Indicators and assessed against predefined Sustainability Performance Targets. Because the promise is about outcomes, the disclosures are about metrics: how each KPI is defined and calculated, why it was chosen, how it fits the issuer's strategy, what target is attached, on what observation dates, which events trigger a change in the bond's terms, and what fallback applies if a target cannot be observed. The detail is in what is a sustainability-linked bond.

What each instrument actually tells a reader

If you follow this data rather than issue it, the two produce different evidence.

A green bond produces a backward-looking audited number: how much of the raised amount was deployed, into which projects, verified by an external auditor covering both the internal tracking method and the allocation. It also produces environmental metrics under Annexure IX-A, which are the Business Responsibility and Sustainability Reporting tables covering energy, water, air emissions, Scope 1 and Scope 2 greenhouse gases, waste and environmental compliance. That framework is explained in what is BRSR.

A sustainability-linked bond produces a forward-looking commitment and then an annual scorecard: up-to-date KPI performance including baselines, and an independent verification report outlining performance against the SPTs, the related impact and the timing of that impact on the bond's financial or structural characteristics. The reviewer's mandate goes wider than on a green bond, covering the relevance and reliability of the chosen KPIs, whether they are materially linked to the issuer's core strategy, the level of ambition of the targets, the reliability of benchmarks and baselines, the credibility of the strategy to hit them, and any material change to methodology or calibration.

SEBI also tells issuers how to benchmark targets, which is a rare piece of prescription. The footnote to Annexure IX-C-B directs a combination of three approaches: the issuer's own performance over time, with a minimum three-year measurement track record recommended where feasible; peer positioning against average or best-in-class performance or industry standards; and reference to science, including science-based scenarios, absolute levels such as carbon budgets, or official targets such as the Paris Agreement and net zero goals, the Sustainable Development Goals and the Kunming-Montreal Global biodiversity framework.

The failure modes are also different

For a green bond, the risk is that the money goes somewhere it should not. SEBI's greenwashing chapter addresses exactly that, and requires disclosure to investors plus, if a majority of debenture holders require it, early redemption. See how to spot greenwashing in green bonds.

For a sustainability-linked bond, the money cannot be misdirected because it was never directed. The risk is a weak target: a KPI chosen because it was already going to improve, or an SPT set below what the issuer would have achieved anyway. That is why the reviewer is asked to certify the level of ambition rather than merely the arithmetic, and why the benchmarking footnote insists on peers and science alongside the issuer's own history.

Between the two, there is also a middle instrument for issuers whose whole business is the thing that needs changing. Transition bonds are a sub-category of green debt security, not a separate label, and carry a GB-T denotation and a dated transition plan: see what is a transition bond. The social equivalent of the green category list is set out in what are social bonds.

Green bonds and sustainability-linked bonds answer different questions, so a reader comparing them is really choosing which evidence to weigh: an audited record of where money went, or a verified score against a target the issuer set. Flock reports public regulatory filings with every claim sourced and dated. What any of it means for your money is your call to make.