UK CBAM cost calculator
UK CBAM is tonnes × emissions per tonne × the sector rate for the quarter you import in, less any carbon price already paid abroad. Enter a commodity code and a tonnage. Until HM Revenue & Customs (HMRC) publishes the binding rates, the result uses its illustrative rates and says so.
| Emissions per tonne | 2.722 tCO2e (HMRC default) |
| Embedded emissions | 272.2 tCO2e |
| Iron & steel rate | £9.69 per tCO2e (HMRC illustrative rate) |
| CBAM before relief | £2,637.62 |
| Carbon price relief | − £0.00 |
HMRC has not published the binding rate for 2027-Q1 yet. This uses its illustrative rate of 16 October 2026, which is not a forecast. The page switches to the binding rate once it is out.
HMRC: if you submit a return that uses default values, you cannot amend it later with actual emissions data.
How the rate is worked out
The Finance Act 2026 sets the formula and SI 2026/809 fills in two steps. The UK ETS price is the mean of all auction clearing prices in the quarter before the import quarter (regulation 3). It is then reduced by the share of the sector's emissions covered by free allowances, scaled by the year's phase-out factor (regulation 4; 97.5% for 2027).
rate = ETS price × [1 − (free allocation % × phase-out factor)]
cement: £58.15 × [1 − (87.1% × 97.5%)] ≈ £8.77
That is HMRC's own worked example, which it rounds to £8.78. HMRC publishes the result for each sector at the start of every quarter from 1 January 2027; the rates for January to March 2027 come out before the end of 2026.
Carbon price relief
If the producing installation paid a carbon price under a qualifying scheme, relief is the effective carbon price × the embedded emissions it applied to (regulations 12 and 13), converted to sterling at HMRC's published rate and rounded down to the penny. It can never exceed the CBAM due. You need a verified carbon pricing verification form to claim it. The calculator applies your figure to every embedded tonne, so it over-states relief if only part of the emissions were priced.
UK CBAM Readiness Pack
A working Excel file, not a report. Five sheets: the dates with what you need done by each, a rolling 12-month threshold test you fill in, a liability estimate covering 570 CN codes across all five UK sectors that prices your own tonnage, and the eight questions to send your suppliers now.
Read this first: the estimate uses HMRC's UK default values, published 16 October 2026, priced at HMRC's illustrative rates. Those rates are not binding: the real ones for early 2027 come out before the end of the year, and you type them into the file when they do. It is for sizing and budgeting, never for a declared figure.
€19 €9 until 30 Nov · one-off payment, instant download, link valid 12 months. Not tax or legal advice.
Sources: SI 2026/809; HMRC, Illustrative CBAM rates and worked example; HMRC, Rates for CBAM; HMRC, Work out your Carbon Price Relief; HMRC default values. Informational only, not tax or legal advice.