The Retroactive Default-Value Correction: Why IR 2026/1740 Means Redoing Your 2026 CBAM Numbers

Most CBAM corrections announce themselves. This one did not.

On 31 July 2026 the Commission published Implementing Regulation (EU) 2026/1740, correcting the default values that importers have been using since the definitive period opened. It entered into force on 3 August 2026. And it applies retroactively from 1 January 2026.

If you used a default value to price, accrue, contract or budget against any 2026 import, the number you used may no longer match the legal text that governs it.

The short version

• IR 2026/1740 corrects Implementing Regulation (EU) 2025/2621, the regulation that sets definitive-period default values.
• It does so by replacing Annex I and Annex IV in full, not by listing individual line-item amendments.
• The corrections address omissions, transcription errors, incorrect production-route indicators, and classifications drawn too broadly to select the intended default.
• Reporting on the regulation indicates that selected aluminium products and unknown-origin precursors are among the affected entries.
• It applies from 1 January 2026, so every default-based calculation made this year sits in scope.

Why "replacing the annex" is the operative detail

Amending regulations usually give you a diff. They say: in row X, replace value Y with value Z. You read the amending act, you find your rows, you are done in an afternoon.

IR 2026/1740 does not work that way. It substitutes Annex I and Annex IV wholesale. That is the correct legal instrument when the errors are scattered across categories and types - omissions, mis-keyed figures, wrong route flags - but it has a practical consequence: you cannot determine what changed by reading the amending act. You have to compare the new annex against the version you actually used, entry by entry, for the CN codes you actually import.

Most importers never saved the version they used. That is the first finding of this exercise for a lot of teams, and it is the more important one.

The error classes, and what each one does to your number

Not all of these corrections are equal. A missing entry is an inconvenience. A wrong production-route indicator is a different order of problem.

Error class	What went wrong	Practical impact	What to re-check
Omission	An entry that should have existed was absent	You may have fallen back to a broader or less favourable default, or treated the good as out of scope	Whether any CN code you import had no usable entry in the old annex
Transcription error	A figure was mis-keyed	Your emissions factor is simply wrong, in either direction	The numeric value for every CN code you used, against the new annex
Incorrect production-route indicator	The wrong route was flagged for a good	Potentially a large multiple, not a rounding error	Route mapping per supplier and per good
Over-broad classification	The entry was too wide to select the intended default	You may have applied a value that was never meant for your good	Whether your CN code now resolves to a narrower, different entry
Unknown-origin precursor treatment	Corrections to how precursors of unknown origin are valued	Propagates upward into every complex good containing that precursor	Complex-goods calculations end to end

The third row is the one to worry about. Production route is the single biggest lever in the CBAM default-value tables. The gap between blast-furnace steel and electric-arc-furnace steel, or between primary and recycled aluminium, is not a few percent - it is the difference between two fundamentally different industrial processes, and the defaults reflect that. We have written before about why your supplier's production route is now a procurement decision; the same logic makes a mis-flagged route indicator an expensive transcription error rather than a trivial one.

Unknown-origin precursors: the quiet multiplier

Most CBAM goods are complex goods. Their embedded emissions are substantially inherited from precursors - inputs your supplier bought from someone else, sometimes without knowing where they were made. The default regime has to say something about that case, and what it says feeds directly into the final figure.

Correct the precursor treatment and you do not correct one number. You correct the base of every calculation that sits on top of it. If you import complex goods and you have been relying on defaults for precursors, assume the cascade has moved and re-run it rather than spot-checking. Our post on how precursor inputs cascade into your certificate bill sets out the mechanics.

What this actually costs you in 2026 - and why that is the wrong question

The instinct is to look at the cash impact and relax. In 2026 the CBAM factor is 2.5%, and the Q1 certificate price was €75.36/tCO₂e with Q2 at €75.28. A default-value error on a single shipment, run through a 2.5% factor, rarely produces a number that frightens a CFO today.

That is the trap. Three reasons the cash number understates the exposure:

1. The declaration is a restatement, not a fresh calculation. Your first annual CBAM declaration is due 30 September 2027 and covers 2026 imports. Whatever you file then has to be defensible against the legal text as corrected - not against the table you happened to download in February.
2. The factor ramps. The same data quality problem, carried forward into your systems and supplier relationships, gets more expensive every year as the free-allocation phase-out proceeds.
3. Contracts may have already moved money. If you have price pass-through or carbon-cost clauses, a corrected default may mean you have over- or under-charged a counterparty on a number that is now wrong. That is a commercial conversation, and it is easier to have early.

The remediation checklist

This is a data exercise, not a legal one. Roughly in order:

1. Re-pull the consolidated annexes. Work from the current consolidated version of IR 2025/2621 as corrected by IR 2026/1740 - not from a cached spreadsheet, and not from a third-party table unless you can trace it to the Official Journal.
2. Rebuild the CN-code-to-entry map. For every CN code you imported in 2026, resolve which annex entry now applies. Watch for codes where a previously broad entry has been narrowed.
3. Re-verify production routes per supplier, per good. If you inferred a route rather than receiving it, this is the moment to ask the supplier directly.
4. Re-run 2026 accruals. Recalculate from 1 January 2026 forward, shipment by shipment, not in aggregate.
5. Quantify and route the deltas. Give finance a per-quarter delta, not a single annual number - quarterly certificate prices differ, and the restatement should reflect that.
6. Check your contracts. Any clause referencing embedded emissions, default values, or carbon cost pass-through should be re-read against the corrected figures. See our clause-by-clause CBAM contract drafting guide.
7. Version-stamp every calculation from now on. Record which default-value table version produced each number, with a date.

The governance lesson

The real finding here is not that some aluminium entries were wrong. It is that CBAM default values are a live reference dataset, and the EU has now demonstrated it will change them retroactively.

Treat them accordingly. Default values belong in the same governance category as exchange rates, tariff schedules and commodity indices: versioned, dated, sourced to a primary publication, and never silently overwritten in a shared spreadsheet. Any team that can answer "which version of the table produced this number, and when did we pull it?" will handle the next correction in an afternoon. Any team that cannot will repeat this exercise from scratch.

There will be a next correction. The annexes are large, the sectors are technical, and the definitive period is young.

What to do this week

• Find out whether anyone on your team saved the pre-August version of Annex I and Annex IV. If not, note that as a gap and fix the process.
• Pull the corrected annexes and diff them against your live CN-code mapping for your top ten import lines by volume.
• Ask your aluminium suppliers specifically to reconfirm production route and precursor origin.
• Put a single owner on the 2026 restatement, with a deadline well ahead of the 30 September 2027 declaration.
• Add a "default value table version" field to whatever system holds your CBAM calculations.

If you are still deciding between defaults and actual supplier data in the first place, that is a related but separate question - we cover the trade-off in CBAM Default Values vs Actual Values. This correction is a reasonable argument for moving to verified actuals sooner: actual values do not get retroactively amended by implementing regulation.