Registration
UK CBAM registration: the £50,000 threshold and the two tests
Updated
You must register for UK CBAM once the value of CBAM goods you import reaches £50,000, looking back over the last 12 months or forward over the next 30 days.
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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)
The two tests
HMRC's policy summary sets the registration threshold at £50,000. On the first day of each month an importer looks back over the preceding 12 months; on any day it also asks whether it expects to import £50,000 or more within the next 30 days.
Source: HMRC: CBAM policy summary
After you become liable
HMRC's factsheet says the liable person will ordinarily have 30 days to register from the day they become liable.
Source: HMRC: CBAM factsheet
Records must be kept for 6 years after the end of the accounting period, and a return can be amended within 3 years of the end of the period it relates to.
Source: HMRC: CBAM policy summary
This page is information, not legal or customs advice.