Check one ETS surcharge line

A freight forwarder in Rotterdam approved an EU ETS surcharge of EUR 513.03 on one container that owed EUR 256.51.

Nothing looked wrong. The carrier named the emission year, quoted an EUA price, printed a figure. What it did not print was the scope factor, and that is where the money was. The box came from a non-EEA port, and on a voyage into or out of the EEA only 50% of the emissions fall inside the system. The line was built as if all of it counted. Doubling 3.11 allowances to 6.22 is invisible in a total.

Three numbers have to be right at the same time on that line, and two of them changed on 1 January 2026.

The first is the phase-in. Shipping companies surrendered allowances for 40% of the emissions reported in 2024, then 70% of those reported in 2025. From 2026 emissions it is complete at 100%. An invoice still resting on the 70% basis is billing last year's rule, and a forwarder checking it against memory will nod it through.

The second is the scope factor, which moves with the voyage, not the calendar. Emissions are 100% in scope between two EEA ports and while at berth in an EEA port. They are 50% in scope on a voyage into or out of the EEA from or to a non-EEA port. Two legs of the same service, two answers, one identical-looking line.

The third is which gases count. Until the end of 2025 the maritime obligation was CO2 only. On 1 January 2026 methane and nitrous oxide entered it, counted as CO2e. On an LNG dual-fuel ship that is not a rounding difference. Run the same Shanghai-Rotterdam box as a 2025 emission and the answer is 2.03 allowances and EUR 150.30; as a 2026 emission it is 3.11 allowances and EUR 256.51.

This is the kind of question a chatbot answers confidently and wrongly. Ask one what a 2026 surcharge should be and it reaches for the 70% phase-in and the CO2-only basis that dominated its training data, true for two years and false since January. Nor can it see your voyage leg, the one input deciding whether you owe half or all of it.

The arithmetic itself is four multiplications per line, each needing a rule you have to look up, across hundreds of lines a month. So the check was built as a browser extension. You type 7 fields off the carrier's ETS statement and the invoice: emission year, voyage leg, CO2 tonnes, CH4 and N2O tonnes as CO2e, the EUA price used, the amount billed, and the surrender deadline. It returns the allowances owed, the correct surcharge, the difference in euro and percent, the gases in scope, and the deadline. On the Rotterdam box it returns: over-billed by EUR 256.52, 100% above the allowances owed. That sentence is the dispute email.

Allowances for a year's emissions are surrendered by 30 September of the following year - for 2026 emissions, 30 September 2027. A correction raised before that date is an adjustment; raised after, it is a negotiation.

A checker that only finds money in your favour is not a checker. Hamburg to Gothenburg, 1.9 tonnes, no methane, billed EUR 120.00: both ports are in the EEA, the whole voyage is in scope, and the correct figure is EUR 156.71. That line is under-billed by EUR 36.71, and a correction invoice is coming.

The calculation is free - no key, no limit, nothing watermarked - in the popup and on a web page running the same code. The paid version works on a different axis: it keeps checked lines as .csv rows and sets reminders 30, 14 and 1 days before the surrender deadline.

A US customs consultant bills $34 to $79 an hour, and independent trade-compliance firms charge $150 to $400 an hour - and they take portfolios, not single lines.