Default values
UK CBAM default values: HMRC's emissions per tonne by CN code
Updated
Without verified emissions data from your supplier, HMRC publishes a default value for each CN code. Multiply it by your tonnes and the sector's rate for the charge.
Email me this result
We will send you these figures and a link back to them. One email, nothing else unless you tick the box.
How this calculator works
- The rates. HMRC's illustrative 2027 rates per tonne of CO2e: iron and steel £9.69, aluminium £9.79, cement £8.78, fertiliser £1.45, hydrogen £9.24. They are illustrative: the rate for each quarter is worked out from the preceding quarter's average UK ETS price. (HMRC: illustrative CBAM rates and worked example)
- How a rate is built. HMRC's worked example for cement: the Q3 2026 average UK ETS price of £58.15, times one minus the sector's 87.1% baseline free allocation times the 97.5% phase-out reduction factor, gives £8.78 per tCO2e. (HMRC: illustrative CBAM rates and worked example)
- Charge, relief and liability. HMRC: the CBAM charge is the imported embodied emissions times the CBAM rate; carbon price relief is the relevant embodied emissions times the effective carbon price; the liability is the charge less the relief. The calculator never lets relief exceed the charge. (HMRC: CBAM policy summary)
- Default values. Where you have no verified supplier data, HMRC publishes a default value per CN code, in tonnes of CO2e per tonne of product: 2.434 for anhydrous ammonia, for example. (HMRC: fertilisers default values)
- Registration. HMRC sets the registration threshold at £50,000 of CBAM goods, tested backward over the preceding 12 months and forward over the next 30 days. The calculator applies the backward test only. (HMRC: CBAM policy summary)
Examples from HMRC's lists
| CN code | Description | Default value, tCO2e per tonne | Source |
|---|---|---|---|
| 26011200 | Agglomerated iron ores and concentrates | 0.494 | HMRC: iron and steel default values |
| 76011010 | Aluminium slabs, not alloyed, unwrought | 2.058 | HMRC: aluminium default values |
| 25070080 | Kaolinic clays (other than kaolin) | 0.240 | HMRC: cement default values |
| 28080000 | Nitric acid; sulphonitric acids | 2.048 | HMRC: fertilisers default values |
| 28141000 | Anhydrous ammonia | 2.434 | HMRC: fertilisers default values |
| 28142000 | Ammonia in aqueous solution | 0.999 | HMRC: fertilisers default values |
| 28342100 | Nitrate of potassium | 1.813 | HMRC: fertilisers default values |
| 28041000 | Hydrogen | 28.378 | HMRC: hydrogen default values |
These are the first codes on each of HMRC's sector lists; every list carries many more. Look your own code up on the sector's page.
Source: HMRC: iron and steel default values
Using a default value
Enter the default value in the calculator's emissions-per-tonne box. For 1,000 tonnes of anhydrous ammonia at 2.434 tCO2e per tonne and the illustrative fertiliser rate of £1.45, the charge is £3,529.30 before any relief.
Source: HMRC: fertilisers default values