Environmental tax,
handled.
Oportax is the platform UK importers use to handle CBAM. Upload your purchases. We do the rest — supplier outreach, verified emissions, audit-ready returns.
From £200/month · 14-day satisfaction guarantee
Built on HMRC draft secondary legislation · Updated continuously
The problem
CBAM is a new tax, complex to compute, and expensive to get wrong.
You owe a new tax from January 2027
UK CBAM applies to imports of aluminium, cement, fertiliser, hydrogen, iron, and steel. If you import more than £50,000 a year in these goods, 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
Use HMRC defaults and you over-pay — they’re set higher than reality on purpose. Underestimate and you face Senior Accounting Officer liability and HMRC penalties.
How it works
Four steps from your purchase data to a filed HMRC return.
Upload your import data
From your customs broker, ERP, or CSV. We accept Customs Declaration Service exports out of the box.
We contact your suppliers
Multilingual outreach. Automatic chasing. Sent from your domain, not ours, so they trust it.
Track liability in real time
Quarterly figures update as supplier data flows in. No more end-of-period scrambles.
File with HMRC
Audit-ready returns generated automatically. Full trail for Senior Accounting Officer sign-off.
Savings
How much could you save?
Most UK importers will overpay their CBAM levy by 20–40% if they rely on HMRC's default emission factors. Verified supplier data eliminates most of that premium. Use the calculator below to estimate your potential saving.
Your imports of steel, aluminium, cement, fertiliser, hydrogen, or iron from outside the UK.
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, audit-ready by default.
Verified supplier emissions data
Typical saving: £30,000–£120,000 per year for mid-market importers
Continuous import classification
Improves classification accuracy from ~90% to >99%
Liability monitoring
Surfaces issues averaging £5,000–£15,000 of avoidable cost per quarter
HMRC return preparation
Saves 40–60 hours of senior finance time per filing cycle
Audit defence
Avoids £15,000–£25,000 in audit response fees
Procurement savings recommendations
Typical additional saving: £20,000–£80,000 per year (Scale tier)
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 HMRC draft secondary legislation 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?
Without verified supplier data, you pay your CBAM levy based on HMRC’s default emission factors — which assume worst-case production methods. That means you’re almost certainly overpaying. 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. The difference between the default rate and your verified rate is your saving. For most mid-market importers, this is £30,000–£120,000 per year.
What if my suppliers don’t respond?
We use HMRC default emission factors as a fallback (which are deliberately punitive) and continue chasing. Most importers find that being able to show the default cost is what finally gets suppliers to provide real data.
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 files your HMRC return.
Can I cancel my subscription?
Yes. We offer a 14-day satisfaction guarantee — full refund if cancelled within 14 days. After that, annual subscriptions are non-refundable for the current period but won’t auto-renew.
Do you submit returns directly to HMRC?
Not yet. HMRC’s CBAM filing API specification is still in development. We generate the return as a fully audit-ready document and CSV. Direct API filing will land before the first return deadline.
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.