UK CBAM registration is triggered when imports of CBAM goods cross £50,000, tested two ways at once: expected imports of £50,000 or more within the next 30 days, or aggregate imports reaching £50,000 over the preceding 12 months. Whichever date arrives first governs. Registration opens by 1 January 2028.
UK CBAM applies to imports of CBAM goods from 1 January 2027. Unlike the EU threshold, which is a mass test, the UK threshold is a value test, and it is assessed continuously rather than once.
The two concurrent tests
| Test | What it asks | When it is assessed |
|---|---|---|
| Forward-looking | Whether the business expects to import CBAM goods valued at £50,000 or more | Across the next 30 days |
| Backward-looking | Whether the aggregate value of CBAM goods imported has reached or exceeded £50,000 | Over the preceding 12 months, assessed on the first day of each month |
Both run in parallel. An importer that never triggers the backward-looking test can still be caught by a single large forward order, and an importer with a steady low-value flow can cross the line on the monthly look-back without any single shipment being significant. The obligation bites on whichever date arrives first.
Why the UK and EU thresholds are not interchangeable
The EU de minimis is a cumulative annual net mass of 50 tonnes of CBAM goods per importer, introduced by Regulation (EU) 2025/2083. The UK threshold is £50,000 by value. The two cannot be converted into one another, and an importer into both markets has to track two entirely different measures on the same shipments. A consignment can sit below one threshold and above the other.
Dates that follow registration
Registration opens by 1 January 2028. The first accounting period is a single 12-month period running 1 January to 31 December 2027, with the first return and any payment due by 31 May 2028. From 1 January 2028 accounting periods become calendar quarters, with returns and payments due on the last working day of the second month after the period ends. HMRC holds a power to vary those periods and deadlines and has indicated it may use it to ease the transition to quarterly accounting.
Sources: GOV.UK CBAM registration collection, Finance Act 2026, Part 5
Tracking two thresholds on one shipment flow is a data problem before it is a tax problem. CBAM solutions covers exposure mapping across both regimes, and the CBAM guide sets out the EU obligations that run alongside the UK ones.