Set the institutional skeleton first. The GX-ETS is the core pillar of Japan's Green Transformation policy, moving from its voluntary phase into a rules-based regime from FY2026: it covers large emitters (roughly 600 companies) whose direct emissions averaged above 100,000 tCO2/yr over FY2023-2025, each required to submit transition plans aligned with the 2050 carbon-neutrality goal. Pricing uses a corridor: for FY2026, a ceiling of JPY 4,300/tCO2 (calibrated to fuel-switching costs) and a floor of JPY 1,700/t (calibrated to energy-saving costs), rising each year from FY2027 by expected inflation plus 3%. Full allowance trading is expected to begin in autumn 2027 under the GX Acceleration Agency, with financial institutions and trading houses admitted subject to eligibility. On flexibility, carbon-credit usage is capped at 10% of annual emissions (J-Credits, JCM credits and CCS-derived credits), and non-compliance is penalized at 1.1x the ceiling price. For a trading house, this is a timetable from which the long-run cost curves of Japanese power, refining, steel and chemicals can be projected.

The live debate is how triggers are set. The secretariat's proposal disclosed at recent rule meetings: monthly average prices standing above the ceiling or below the floor for three consecutive months activate measures; a monthly average only counts in months with dealing on at least 70% of trading days; a volume test also applies - if for more than a month after the December compliance notice no sell orders at or below the ceiling appear, that too triggers. Above the ceiling, the remedy is "deemed holding": a company paying the ceiling price is deemed to hold the allowance, effectively injecting liquidity; below the floor, the GX Acceleration Agency runs off-market single-price reverse auctions to buy back allowances, with the volume formula and maximum repurchase price kept confidential against strategic quoting. Expert opinion splits between 3-month and 6-month trigger windows - too short invites false triggers from temporary shocks, too long hollows out the corridor itself; banking rules and allowance disclosure remain on the agenda beyond the 27 October session. These details will determine the quality of the carbon-price signal once trading opens in autumn 2027.

The cadence of the cost curve matters more than the price itself. Third-party asset-level modelling lays out a clear three-phase path: in FY2026-FY2032, free allocation follows slowly-declining benchmarks (coal generation just 0.2%/yr, gas 0.06%/yr), leaving most covered companies with sellable surplus - aggregate net earnings peaking near JPY 300bn in FY2030; from FY2033, power-sector auctioning begins and the position inverts; by FY2040 the net cost reaches about JPY 1.2 trillion as auctioned volumes rise to 100% of power-sector allowances. Scaled to a single asset: a 1 GW coal plant at 70% utilization emits roughly 5 MtCO2/yr, implying about JPY 25bn of annual compliance cost at a 2036 corridor midpoint of JPY 5,000/t - more than most Japanese coal units earn. The other structural variable is J-Credit supply-demand: annual demand of about 3 Mt against roughly 1 Mt of supply, on which basis market analysts project credit prices of $27.6-41.4/t in 2027, breaking above $41.5 (over JPY 6,000) by 2030.

What it means for SNSUC. First, surplus free allocation in FY2026-FY2032 means carbon cost is not yet a direct variable in Japan-related trade - Japanese counterparties' cost pressure still comes mainly from energy and FX, consistent with our earlier assessment. Second, from FY2033 carbon costs become explicit and concentrate on coal-heavy regional utilities; the long-run cost curves of Japan's energy-intensive industries (power, steel, cement, refining) will be redrawn, and multi-year supply agreements with Japanese buyers should carry carbon pass-through assessment now rather than after the market opens. Third, the 10% offset cap and the J-Credit supply gap imply genuine future Japanese demand for international carbon assets and reduction-project cooperation - an interface the company can position against early in green trade and data services. This article is market observation based on public data and does not constitute investment advice.

Author: Qiu Binbin (Shanghai New Shell Union Chemical Co., Ltd.)