CBAM Certificate Cost Formula: Phase-In Factor and Pricing Rules

The CBAM definitive phase started on January 1, 2026, which means certificate obligations are no longer theoretical. But "how much will this actually cost me" turns out to be a harder question than most guides make it look — the answer depends on four separate inputs, one of which (the phase-in factor) most importers haven't fully internalized yet, and the payment calendar itself changed under the EU's October 2025 simplification package.

This is the full calculation, sector by sector, with worked examples. For the current ETS price, see the live price banner above.

All data in this article is sourced from EU Regulation 2023/956, IR (EU) 2025/2548, IR (EU) 2025/2621, and the European Commission's official CBAM certificate price publication (April 7, 2026). Last verified: July 2026.

The four inputs

1. Embedded emissions (tCO2e) Either verified actual data from your supplier, or EU default values if you don't have it. Default values carry an extra markup on top: 10% in 2026, rising toward 30% by 2028 for most goods. Defaults aren't the "easy path" — they're the expensive path, deliberately. (Source: IR (EU) 2025/2621, default value methodology)

2. The CBAM factor (free allocation adjustment) This is the percentage by which free allocation offsets your embedded emissions liability. It phases in on the inverse curve of free EU ETS allowances:

Year	CBAM factor (free allocation offset)	Net liable share
2026	97.5%	2.5%
2027	95%	5%
2028	90%	10%
2029	77.5%	22.5%
2030	51.5%	48.5%
2031	39%	61%
2032	26.5%	73.5%
2033	14%	86%
2034	0%	100%

Source: Regulation (EU) 2023/956, Annex VIII — CBAM factor phase-out schedule

In 2026, 97.5% of your embedded emissions are offset by the free allocation adjustment. Only the remaining 2.5% generates a certificate obligation. By 2034, the free allocation offset drops to 0% and the full embedded emissions become liable.

Your 2026 bill is a tiny fraction of what the same import volume will cost by 2030. Budget planning should use the 2030 number, not the 2026 one.

3. Carbon price paid at origin If your supplier has paid a verifiable carbon price in the country of production, that amount can be deducted from your CBAM obligation — with documentation.

4. The certificate price For the 2026 compliance year, certificate prices are a quarterly average of EU ETS auction clearing prices. From 2027 onward, it reverts to a weekly average. As of late June 2026, EU ETS allowances were trading around €80/tonne. The first official certificate price (Q1 2026) was published on April 7, 2026 at €75.36/tCO₂. (Source: European Commission, DG TAXUD — Price of CBAM certificates page)

The calendar changed too

• Certificate sales start February 1, 2027, not January 2026 — you'll buy certificates in 2027 to cover 2026 imports.
• Annual declaration deadline: September 30 (moved from May 31) of the following year.
• Quarterly holding requirement: 50% of year-to-date embedded emissions (down from 80%).

If a source you're reading still describes the original 2023 timeline, it's out of date.

Formula

Step 1: Emissions subject to CBAM = Embedded emissions − (Benchmark x CBAM factor x Mass)

Step 2: Certificate obligation (tCO2e) = max(0, Emissions subject to CBAM)

Step 3: Certificate cost (EUR) = Certificate obligation x Certificate price

Where embedded emissions uses default-value markup if you don't have verified supplier data.

CBAM factor in 2026 is 97.5% — meaning 97.5% of your embedded emissions are offset by the free allocation adjustment. Only the remaining 2.5% generates a certificate obligation. By 2034, the factor reaches 0% and the full embedded emissions are liable.

Steel: worked example

Steel (CN 7206–7229, 7301–7306) has three common production routes, each with very different emissions intensity:

Route	Typical benchmark (tCO2e/tonne)
BF-BOF (blast furnace)	1.370
DRI-EAF (direct reduced iron)	0.481
Scrap-EAF (recycled)	0.072

Source: IR (EU) 2025/2621, Annex I — Steel sector benchmarks

Note: steel also has a specific quirk worth knowing — indirect emissions (from purchased electricity) are exempt for most steel CN codes, unlike aluminium below. Only direct process emissions count toward your certificate obligation for most steel imports.

Example: 1,000 tonnes of BF-BOF steel, imported in 2026

• Verified embedded emissions: 1,000 x 1.9 tCO2e/tonne = 1,900 tCO2e
• Free allocation offset: 1.370 x 97.5% x 1,000 = 1,335.75 tCO2e
• Emissions subject to CBAM: 1,900 − 1,335.75 = 564.25 tCO2e
• No origin carbon price deduction
• Certificate price: ~€80/tonne

2026 cost: 564.25 x €80 ≈ €45,140

Run the same shipment at the 2030 CBAM factor (51.5%) and an illustrative €90/tonne price: free allocation becomes 1.370 x 51.5% x 1,000 = 705.55 tCO2e, leaving 1,194.45 tCO2e liable — ≈ €107,500.

Aluminium: worked example

Aluminium (CN 7601–7616) is different from steel in one important way: it's electricity-intensive, and indirect emissions are fully in scope. That means the carbon intensity of the electricity grid where the aluminium was smelted matters enormously — a smelter running on hydropower and one running on a coal-heavy grid can have wildly different embedded emissions for the same tonnage.

• Typical unwrought aluminium benchmark: 1.423 tCO2e/tonne, before grid-factor adjustment
• If the exporting country's grid emission factor is high, actual embedded emissions can run well above benchmark

Example: 500 tonnes of unwrought aluminium, imported in 2026, coal-heavy grid

• Verified embedded emissions (direct + indirect): 500 x 2.6 tCO2e/tonne = 1,300 tCO2e
• Free allocation offset: 1.423 x 97.5% x 500 = 693.98 tCO2e
• Emissions subject to CBAM: 1,300 − 693.98 = 606.02 tCO2e
• Certificate price: ~€80/tonne

2026 cost: 606.02 x €80 ≈ €48,482 — but this is the sector where sourcing decisions (which grid your supplier's smelter sits on) move the number more than almost any other factor. Two suppliers with identical production processes can produce very different CBAM bills purely based on electricity mix.

Cement: worked example

Cement (CN 2523, plus kaolin under 2507) is dominated by calcination emissions — a process emission from converting limestone to clinker, not a fuel-combustion emission, which means efficiency improvements at the plant only go so far in reducing it.

• Typical benchmark: 0.666 tCO2e/tonne
• Key variable: clinker-to-cement ratio — cement blended with more supplementary materials (fly ash, slag) has proportionally lower embedded emissions than pure clinker cement

Example: 2,000 tonnes of cement, imported in 2026

• Verified embedded emissions: 2,000 x 0.7 tCO2e/tonne = 1,400 tCO2e
• Free allocation offset: 0.666 x 97.5% x 2,000 = 1,298.70 tCO2e
• Emissions subject to CBAM: 1,400 − 1,298.70 = 101.30 tCO2e
• Certificate price: ~€80/tonne

2026 cost: 101.30 x €80 ≈ €8,104

Fertilizer: worked example

Fertilizer (CN 2808, 2814, 2834, 3102, 3105) is the most heterogeneous category — benchmark values range from 0.173 to 1.522 tCO2e/tonne depending on the specific CN code, because ammonia (produced from natural gas) is a precursor for most nitrogen fertilizers, and the emissions intensity depends heavily on the production pathway and the exporting country's natural gas pricing and access.

Because the range is so wide, there's no single representative example worth generalizing — the CN code and production pathway matter more here than in any other CBAM sector. This is the category where checking your specific product's benchmark, rather than assuming a sector average, matters most.

Common mistakes

Assuming this year's cost reflects reality. The real financial exposure shows up in 2029–2030, when the free allocation offset drops from 77.5% to 51.5% in a single year.

Defaulting to default values because verified data feels like extra work. The markup exists to discourage exactly this. Getting real emissions data from your supplier now, while the numbers are still small, is far cheaper than switching after 2028.

Not tracking the origin carbon price deduction. If your supplier operates in a country with any form of carbon pricing, that's real money left on the table without documentation.

Treating indirect emissions rules as uniform across sectors. Steel's indirect exemption and aluminium's full indirect scope are opposite rules within the same regulation — assuming one applies to the other produces the wrong number.

Getting verified data from suppliers who've never heard of CBAM

For steel, aluminium, and cement, verified data usually needs to come from the producer's own process records — furnace type, fuel mix, and for aluminium, the specific electricity contract or grid connection. If your supplier has never been asked for this before:

1. Start with production route (which furnace/process type) — this alone often narrows the estimate more than any other single data point
2. Ask for their most recent annual energy/fuel consumption figures, not projected or nameplate figures
3. For aluminium specifically, ask about the electricity source directly — grid-supplied, dedicated hydro/renewable PPA, or on-site generation all produce very different numbers
4. Document any carbon price they've already paid — this is the deduction most importers forget to claim

Try it yourself

Running these numbers by hand across a multi-product, multi-supplier import book gets unwieldy fast — that's exactly the problem CBAMTrack's calculator is built to solve, with the phase-in factor, current-year pricing rule, and sector benchmarks built in.