IS 1893:2025 Redraws the Hazard Map: What the New Seismic Code and Zone 6 Mean for Earthquake Underwriting and Retrofit Credits

In late 2025 the Bureau of Indian Standards released a revised earthquake design code, IS 1893:2025, built on Probabilistic Seismic Hazard Assessment (PSHA) rather than the older deterministic zoning. It introduced a new highest-risk band, Zone 6 (zone factor Z = 0.75), across the Himalayan arc covering Jammu and Kashmir, Ladakh, Himachal, Uttarakhand, Sikkim, North Bengal and the Northeast up to Arunachal Pradesh. The revised map widened the share of India's land area classified as moderate-to-high seismic risk, pushing it to roughly three-fifths of the country.

Then, on 3 March 2026, BIS withdrew the 2025 version through a gazette notification and restored IS 1893:2016. The Ministry of Housing and Urban Affairs had flagged construction cost escalation (estimated at 10 to 15% for buildings in Zones V and VI, and up to 50% for some infrastructure) and inadequate stakeholder consultation. Several geologists pushed back publicly on the reversal.

For a structural engineer, the law of the land is once again the 2016 code. For an underwriter, that is the wrong conclusion to draw. The 2025 draft did not invent new faults. It published, in an official BIS document, the regulator's own best probabilistic read of where the ground shakes hardest. That read does not expire because a design code was rolled back over cost politics.

A broker who treats the 2025 map as dead loses a defensible, science-backed argument for both rate relief on strong buildings and rate adequacy on weak ones. The map is now a free, government-issued underwriting input that no rival has paid for.

The timing also matters. The 2025 draft sat in the public domain long enough for catastrophe modellers, reinsurers and consulting structural engineers to absorb it. That knowledge does not unwind. A reinsurer who updated its view of the Himalayan tail in late 2025 is not going to forget what it learned because a domestic gazette restored the older code. The broker who understands this gap between what is legally mandated and what the market actually believes is the one who can price ahead of the curve rather than behind it.

Indian property and engineering policies have priced earthquake off the IS 1893 zone (II to V) for decades, usually as a fixed add-on rate to the material damage cover. That is a blunt instrument. A Zone IV factory in Delhi and a Zone IV warehouse in a Gangetic basin town with deep soft soil carry very different real exposures, yet they often attract the same earthquake loading.

The deterministic four-zone approach answers only one question: what is the maximum credible shaking here? PSHA answers a more useful one for insurance: what is the annual probability of exceeding a given ground motion? That is the same logic a catastrophe model uses, and the same logic that should drive a rate.

The 2025 draft made three things visible that the 2016 map blurs.

• Soil amplification matters as much as the zone. Soft alluvial soils amplify shaking. Two buildings in the same district can differ by a full damage band because one sits on rock and one on reclaimed soil.
• The Himalayan front is not uniform. Carving out Zone 6 admits that parts of the frontal thrust deserve loading well above old Zone V. A blanket Zone V rate under-prices those districts.
• Several cities quietly moved up. The draft upgraded a number of urban centres into higher bands, which is exactly where commercial accumulation sits.

For a multi-location corporate, pricing earthquake off a flat zone rate means cross-subsidising the worst sites with the best ones. The 2025 hazard data lets a broker break that pooling open and argue each location on its merits. See our note on catastrophe modelling for the Indian subcontinent for how probabilistic loss curves translate into rate.

There is a fairness dimension too. A client whose flagship plant sits on rock in a stable district has been quietly funding the under-priced sites elsewhere in the market for years. PSHA-grounded rating lets that client claim the credit it has earned, while the genuinely exposed sites carry a rate that reflects their real annual exceedance probability. That is not a tougher market for the buyer. It is a more honest one, and a broker who can explain it earns trust that survives the renewal.

The value a broker adds here is translation: turning a hazard map into a building-specific argument. That needs three inputs sitting side by side.

1. The 2025 hazard band for the exact pin location, not just the city. District and sub-district granularity matters because soil and fault proximity change over short distances.
2. The structural design basis of the building. Which code year was it designed to? IS 1893:1984, 2002, 2016 or the withdrawn 2025 draft? A building voluntarily designed to the 2025 loading is materially stronger than its neighbour and deserves to be priced that way.
3. The construction type and vintage. Reinforced concrete moment frames with ductile detailing behave very differently from unreinforced masonry or non-ductile RC built before 2002.

Where a building sits in a band the 2025 draft pushed upward, the honest underwriting answer is a higher earthquake rate, and the broker should pre-empt that with a mitigation story rather than be ambushed at renewal. Where a building was engineered to a higher standard than its location demands, the broker has a credit argument.

What to pull from the client before renewal

• Structural drawings and the design code year stated on them.
• Any third-party structural assessment or retrofit report.
• Soil investigation reports, which reveal the amplification risk the zone alone hides.
• A clear statement of replacement cost, because earthquake claims are total-loss-shaped and sum insured adequacy decides whether the cover actually responds.

A desk pricing off the postal address and a flat zone code will never ask for any of this. That information asymmetry is the broker's edge, and it is precisely what turns a routine renewal into a priced-on-evidence negotiation. The broker who arrives with drawings, soil reports and a code-year profile is no longer arguing about rate in the abstract. They are arguing about a specific building whose strength is documented, and that is a conversation the insured wins far more often than not.

The most commercially useful move the 2025 data unlocks is the retrofit credit. Indian earthquake rating has historically given almost no structured recognition to seismic strengthening. A client who spends on jacketing columns, adding shear walls, base isolation or bracing typically sees no rate benefit, because the rating engine only reads the zone.

That is leaving money on the table for good risks. A retrofit credit argument has three legs.

• Evidence of the hazard. The 2025 band shows the regulator's own probabilistic view that this location is more exposed than the flat zone implies. That justifies why retrofit was sensible and why it should be rewarded.
• Evidence of the strengthening. A signed structural engineer's certificate stating the building now meets or exceeds a defined performance level, with drawings and a method statement.
• A translation into expected loss. Retrofit lowers the probable maximum loss for a given shaking intensity. If a surveyor or cat model can show the PML moving down a band, the rate should follow.

The same logic runs in reverse for project risks. A construction all risks placement in a re-zoned district where the contractor is still designing to 2016 loading carries a real gap, and a broker who flags it early protects both the client and their own errors-and-omissions position. Engineering covers in particular should be stress-tested against the 2025 picture rather than the rolled-back code.

Earthquake is an accumulation peril, not just a per-risk one. A single Himalayan-front event can hit many policies at once, which is why treaty reinsurers and GIC Re care about zonal aggregation far more than about any individual building.

The 2025 map matters at the portfolio level for three reasons.

First, catastrophe model vendors recalibrate to the best available hazard science, and PSHA-based national codes feed those models. Even with the design code withdrawn, the underlying hazard curves that informed the 2025 draft will continue to shape vendor models used in treaty pricing. An insurer whose primary rating still reads the 2016 four-zone map while its reinsurer prices off updated PSHA curves is structurally mismatched.

Second, accumulation control needs the finer geography. A book heavy in newly highlighted districts carries more tail risk than the old zone code suggests. Brokers placing large multi-location programmes should expect reinsurers to ask sharper questions about Himalayan-belt and soft-soil exposure. Our piece on nat-cat accumulation across multi-location corporates walks through how to map and cap this.

Third, treaty renewals will reflect the conversation even if the code does not. Reinsurers do not wait for a domestic gazette to update their view of Indian seismic tail. If global cat capacity tightens, the marginal location in a re-highlighted district is where capacity gets rationed first.

For the broker, the practical step is to run the client's locations against the 2025 bands now, before the next treaty cycle prices it in. Walking into a renewal with the accumulation already mapped is a far stronger position than reacting to a reinsurer's surprise loading.

Earthquake claims in India fail less often on whether the peril is covered and more often on quantum and adequacy. The 2025 hazard re-rating is a good moment to fix the wordings before a loss, not after.

The recurring failure points are well documented.

• Under-insurance and the average clause. Earthquake losses are large and frequently total. If the sum insured is set on book value or a stale reinstatement value, the average clause bites hard at exactly the moment the client needs full indemnity. A re-rating exercise should always re-check valuation.
• Standard exclusions that surprise the insured. Loss or damage to retaining walls, foundations below the lowest basement, and certain ground-movement consequences are often sub-limited or excluded. Clients assume a quake policy pays for everything the quake touched. It does not.
• Earthquake fire versus earthquake shock. Some older wordings treat earthquake fire and earthquake shock as separate insured perils with separate opt-ins. A client who bought one and not the other has a coverage hole that only appears in the claim.

Many Indian earthquake disputes turn on the difference between damage caused by shaking and damage caused by subsequent ground settlement or liquefaction. Confirm the wording covers the full causal chain.

Business interruption sits downstream of all this. A quake that closes a plant for months can dwarf the material damage, yet earthquake BI is frequently under-bought. Our note on earthquake insurance claims settlement covers the surveyor and quantum battles in detail. The broker's job at re-rating is to make sure the cover that responds is the cover the client thinks they have.

Pulling this together, here is the sequence a broker can run on any property or engineering account exposed to earthquake, regardless of the code's legal status.

1. Geocode every location to the 2025 hazard band. Use the pin, not the city. Flag any site that moved up versus the 2016 zone, and any site on soft soil.
2. Pull the structural basis. Capture the design code year and construction type for each material location. Separate the strong buildings (a credit story) from the weak ones (a mitigation story).
3. Re-test the sum insured and valuation. Confirm reinstatement basis and current replacement cost so the average clause cannot ambush a total loss.
4. Audit the earthquake wording. Check earthquake fire and shock are both in, check the foundation and retaining-wall position, and check business interruption indemnity periods are realistic for a rebuild.
5. Build the credit and the mitigation file. For strong sites, assemble structural certificates and frame retrofit as a lower PML. For weak sites, present a costed strengthening roadmap so the insurer sees a managed, improving risk.
6. Map accumulation before the treaty cycle. Aggregate the book by 2025 band so you can answer reinsurer questions before they are asked.

Where the broker wins

The broker who does this is no longer a price-taker on earthquake. They walk into the renewal with the regulator's own hazard science, a building-by-building strength profile, clean valuations and an accumulation map. That is a defensible case for rate relief on the good risks and a credible, costed plan on the bad ones. A desk pricing off a flat, rolled-back zone code has none of it, and that gap is exactly the value a sharp intermediary sells.