Environmental tax,
handled.
Oportax is the CBAM platform built for UK importers. Upload your purchases. We do the rest — supplier outreach, verified emissions, and a return with an audit trail behind every figure.
Built on the UK CBAM regulations, including the Emissions and Verification Regulations made 8 September 2026 · Updated continuously
Does UK CBAM apply to you?
Test 1 — next 30 days
Do you expect to import £50,000 or more of CBAM goods in the next 30 days?
Test 2 — rolling 12 months
Have you imported £50,000 or more in the previous 12 months, checked on the 1st of each month?
CBAM goods — five sectors
Aluminium, cement, fertiliser, hydrogen, and iron and steel. Imports before 1 January 2027 do not count.
Meet either test and you must register with HMRC, report embedded emissions, and pay the levy.
The problem
CBAM is a new levy, complex to compute, and expensive to get wrong.
You owe a new levy from January 2027
UK CBAM applies to imports of aluminium, cement, fertiliser, hydrogen, iron, and steel. If you import £50,000 or more of these goods in a rolling 12-month period, or expect to in the next 30 days, you must register, calculate embedded emissions, and file with HMRC.
Getting it right is complex
Embedded emissions must come from your overseas suppliers. Each in a different language, on different systems, with different verification standards. Then it has to roll up into UK ETS-linked carbon prices.
Getting it wrong is expensive
HMRC has not published UK default values yet, and there will be one per product. Verified supplier data lowers the charge only where your supplier beats the default. Underestimate and you face HMRC penalties.
How it works
Four steps from your purchase data to a filed HMRC return.
Upload your import data
From your customs broker, your ERP, or a CSV. Column names are matched for you — there is nothing to reformat by hand.
We contact your suppliers
Multilingual outreach with automatic chasing. We send on your behalf, with your name in the sender line and your own contact copied in. You can send the first one yourself from your mailbox, which we recommend, or authenticate your domain if you have IT support.
Track liability in real time
Quarterly figures update as supplier data flows in. No more end-of-period scrambles.
File with HMRC
Returns assembled from your own data, with an audit trail behind every figure.
Savings
How much could you save?
HMRC has not published UK default values yet, and there will be one per product. Verified supplier data lowers the charge only where your supplier beats the default. Where your suppliers are dirtier than the default, it flatters them. Use the calculator below to see the arithmetic for your imports.
Your imports of aluminium, cement, fertiliser, hydrogen, or iron and steel from outside the UK.
HMRC's default values will be global averages. Verified supplier data only lowers your levy if your suppliers beat that average — this is your assumption, not ours.
What's included
Everything you need.
Nothing you don't.
Oportax replaces spreadsheets, supplier chasing, and end-of-quarter scrambles. Everything is in one place, with an audit trail behind every figure by default.
Verified supplier emissions data
Prove your suppliers beat the global-average default — the only route to a lower levy
Continuous import classification
Every line matched against the HMRC commodity-code scope, flagged when a code needs review
Liability monitoring
Liability moves as supplier data lands — no end-of-period surprises
HMRC return preparation
Returns assembled from your data, with an audit trail behind every figure
Audit defence
Every figure traceable to its source document and a named, dated emission factor
For your suppliers
Submit once. Reuse across every UK customer.
Your overseas suppliers can use Oportax too — for free. They provide their emissions data once, and any UK buyer importing from them gets verified figures automatically. No more chasing the same data twice.
Ready to reduce your CBAM levy?
Built for UK importers
Not adapted from EU products.
Not bolted onto an ESG dashboard.
Designed from the UK CBAM regulations up.
When can I start using Oportax?
Sign up today. UK CBAM applies from 1 January 2027, but supplier outreach should start now — getting verified data back takes months. Onboard early and have your 2027 baseline ready.
How does Oportax actually save me money?
HMRC has not published UK default values yet, and there will be one per product. Verified supplier data lowers the charge only where your supplier beats the default. Where your suppliers are dirtier than the default, it flatters them. Oportax makes it easy for your suppliers to submit their actual emissions data, and easy for you to access and use it on an ongoing basis. Your saving is arithmetic: tonnage × the emissions difference between your suppliers and the default × the CBAM rate. Use the calculator to see the numbers for your imports.
What if my suppliers don’t respond?
We use default emission values as a fallback and continue chasing. The request shows the supplier what the default basis costs on your consignments, which gives them a concrete reason to send their own figures.
How does the free CBAMcheck tool relate to Oportax?
CBAMcheck is a one-off snapshot estimate of your exposure. Oportax is the platform that keeps that estimate accurate, contacts your suppliers for verified data, and prepares your HMRC return for you or your customs agent to submit.
Can I cancel my subscription?
Yes. We offer a 14-day satisfaction guarantee — full refund of everything paid if cancelled within 14 days. After that, monthly subscriptions can be cancelled at any time with 30 days’ notice, and annual subscriptions run to the end of the paid year. Subscriptions renew automatically; we email a reminder at least 30 days before an annual renewal, and cancelling before the renewal date stops it.
Do you submit returns directly to HMRC?
HMRC has not published a filing API specification. We generate the return as a document for review and a CSV for HMRC's process, with the audit trail behind every figure.
What about EU CBAM?
EU CBAM is a separate regime. We focus exclusively on UK CBAM. EU CBAM support is on the roadmap for 2027.
Where is my data stored?
Securely stored and encrypted. We do not share data between customers without explicit permission.
2027 is closer than you think
Get your 2027 baseline
in place.
Sign up today or book a 20-minute call and we'll walk through your import profile, the work involved, and how Oportax handles it.