It's an easy assumption to make: HMRC has publicly given 2028 as a date, so it reads like the deadline. But it's a grace period bolted onto a trigger that's already running — not a starting gun.
Registration is a rolling, dual test — not a fixed calendar date.
You trigger a registration obligation the moment either of two conditions fires: your trailing 12-month value of CBAM-good imports exceeds £50,000 (checked on the 1st of every month), or you reasonably expect to cross that threshold within the next 30 days — whichever happens first. Once triggered, you're normally required to register within 30 days.
That's a monitoring obligation, not a wait-and-see one. A business importing steadily could trigger in March 2027, June 2027, or any month depending on volume — the date is set by your own import pattern, not by a fixed point on the calendar. HMRC's own guidance, published 16 July 2026, describes exactly this mechanic and gives a worked example: import £70,000 of CBAM goods checked on 1 January 2028 against the trailing 12 months, and you're liable to register from that date — regardless of any easement.
HMRC has separately confirmed a first-year easement: anyone who triggers registration during 2027 gets until 31 January 2028 to actually complete registration, rather than the standard 30-day window. That's real, and it's useful — but it only extends the registration paperwork deadline. Your liability starts accruing from the trigger date, and your record-keeping duties run from the trigger date too. If you triggered in March 2027 and wait until January 2028 to register, you still owe records and potentially CBAM charges back to March.
Here's a detail that explains the easement rather than undermining it: HMRC's own record-keeping guidance, published 16 July 2026, states plainly that "registration for CBAM will open by 1 January 2028." The online service you'd actually use to submit a registration doesn't exist before then — so the first-year easement isn't extra leniency, it's a practical necessity. HMRC couldn't hold 2027 triggers to a normal 30-day paperwork deadline when there's no service to file that paperwork through.
Don't read that as "nothing happens until 2028." The trigger, your liability, and your record-keeping obligation are all live from your trigger date in 2027 regardless of when the portal opens. What HMRC's guidance describes is when you can go and formally submit your details — including estimated weights of CBAM goods by sector for the next 12 months — not when the underlying obligation begins. The practical read for 2027: it's your data collection year. The paperwork step, however delayed, doesn't buy you time on the substance.
The only way to know if you've already triggered is to run your numbers.
Check whether your imports trigger registration →