CBAM's definitive period is set for 2026. The transitional phase ends and importers pay on actual embedded carbon, with free allowances stepping down from 2026 and reaching zero by 2034. The first batch covers only six sectors — steel, aluminium, cement, fertiliser, electricity and hydrogen — petrochemicals are not on it.

But 'not in the first batch' is not 'not touched'. On SNSUC's transfer chain, any downstream buyer with a refining footprint already sees a PCF (product carbon footprint) lead clause in the contract template — fail to deliver batch-level carbon data and the title transfer stalls. We compute a SHA-256 fingerprint of each batch's PCF in the browser and attest it on-chain, so both regulators and buyers can recompute independently instead of taking our word.

Keep two things separate. CBAM is an EU-border tax, it governs the entry into the EU. Our SHA-256 attestation is about making title and carbon data verifiable, it governs trust cost across the whole chain. One tracks the policy calendar, the other tracks our own data backbone. Petrochemicals stay allowance-free until 2034, but ESG due diligence and bank credit already treat carbon data as a hard metric — earlier is cheaper than later.

To the trading desk: for any long-term transfer framework signed from 2026, lock the carbon-data delivery clause into the schedule; do not wait for the first cargo to reach the EU shore. Cross-chain warehouse-receipt interoperability lets that attestation circulate a second time between banks and buyers, and pledge lending also compresses from T+3 to T+0 — carbon compliance and working-capital turnover sit on the same chain.