Worked example · fictional importer, real engine output
From supplier spreadsheets to a defensible CBAM number.
Meet Fenland Steel & Cladding Ltd (fictional) — a mid-size importer of steel, aluminium and cement. Below is their first half of 2027 exactly as our engine processed it: the import ledger their broker exports, two supplier files of very different quality, and what comes out the other end. Every number on this page is real engine output, not a mock-up.
1 · What goes in: the import ledger
A CSV like any broker system produces. No re-keying, no special format — headings like “Entry date”, “CN code” or “Net mass (kg)” are understood as-is.
| Ref | Date | Code | Goods | Mass | Customs value | Supplier |
|---|---|---|---|---|---|---|
| MRN-001 | 15 Jan 2027 | 72081000 | Hot-rolled coil | 24 t | £18,400 | Anhui Steel |
| MRN-002 | 20 Feb 2027 | 73181500 | Bolts | 3.2 t | £9,500 | Anhui Steel |
| MRN-003 | 5 Mar 2027 | 76011000 | Primary aluminium | 18 t | £42,000 | Baotou |
| MRN-004 | 28 Mar 2027 | 76020000 | Aluminium scrap | 12 t | £8,000 | — |
| MRN-005 | 11 Apr 2027 | 72041000 | Ferrous scrap | 5 t | £3,000 | — |
| MRN-000 | 19 Dec 2026 | 72081000 | Hot-rolled coil | 10 t | £7,600 | Anhui Steel |
| MRN-006 | 2 Apr 2027 | 25231000 | Cement clinker | 30 t | £4,100 | — |
2 · What goes in: two supplier files
Anhui Steel — the tidy one
Filled in our supplier data template, independently verified, covers the coil and the bolts including the crude-steel precursor inside them.
Baotou Alu — the real world
- Sheets renamed (“emissions data FINAL v3 (2)”) and reordered
- “Instalation name” — label typo, columns shifted
- European decimal commas (16,50000) and units typed into number cells (“1.9 tCO2e/t”)
- Commodity codes with dots, and a 10-digit TARIC code
- One intensity given in kgCO2e per tonne (1925) — a ×1,000 error waiting to happen
- A leftover example row, a TOTAL row, a formula whose result was never saved
- No independent verification
The messy file still parses — nothing is silently guessed. Every value the engine keeps records which sheet, cell and heading it came from, and every problem comes back as a plain-English note the supplier can act on:
VERDICT: NEEDS FIXES — declaration built, but 4 problem(s) must be fixed
[emissions data!C9] intensity 1925 looks like kgCO2e per tonne, not tCO2e
— row skipped. If it really is kilograms, divide by 1,000
[emissions data!A6] 10-digit TARIC code 7604101000 truncated to 8 digits
[emissions data!C5] decimal comma assumed (European number format)3 · What comes out: every line, priced or explained
| Ref | What the engine decided, and why | Charge | Status |
|---|---|---|---|
| MRN-001 | Verified supplier data: 24 t × 1.925 tCO2e/t direct + slab precursor 25.2 t × 2.1 = 99.12 tCO2e | £4,881.66 | priced |
| MRN-002 | Same verified declaration covers the bolts: 6.72 tCO2e — downstream fasteners are in scope | £330.96 | priced |
| MRN-003 | Supplier file parsed, but the data is unverified — the engine refuses to price on it; awaiting default values | — | pending |
| MRN-004 | Aluminium scrap is not in the Schedule 16 goods table — no charge | £0 | out of scope |
| MRN-005 | Ferrous scrap is an explicit “Except:” exclusion in Schedule 16 — no charge | £0 | out of scope |
| MRN-000 | Imported 19 Dec 2026 — before commencement, so outside the tax entirely | £0 | no charge |
| MRN-006 | Covered cement, no supplier data — priced the moment HMRC's default values publish | — | pending |
£5,212.62
liability known today, at a clearly-labelled scenario rate of £49.25/tCO2e
105.84 tCO2e
verified embodied emissions across the priced lines, with per-line provenance
1 Apr 2027
the £50k threshold trips (rolling covered value £69,900) — register by 31 Jan 2028
4 · Building towards the return
The same data, grouped the way the draft rules say returns will work (per 8-digit code, actual vs default). Period: all of 2027, return and payment due 31 May 2028.
| Code | Emissions basis | Tonnes | tCO2e | Charge |
|---|---|---|---|---|
| 25231000 | default values (awaiting publication) | 30.000 | — | — |
| 72081000 | actual — verified supplier data | 24.000 | 99.12000 | £4,881.66 |
| 73181500 | actual — verified supplier data | 3.200 | 6.72000 | £330.96 |
| 76011000 | default values (awaiting publication) | 18.000 | — | — |
| Total | 75.200 | 105.84 | £5,212.62 |
Want this for your imports — or your clients'?
Importers: join the waitlistjoin the waitlist at cbamreturn.co.uk and start supplier data collection before 2027 does it to you. Customs brokers and forwarders: see partnering with CBAMReturncbamreturn.co.uk/brokers or email hello@cbamreturn.co.uk.
Fictional company; genuine engine output (methodology draft-2). Rate shown is a labelled scenario — the Q2 2026 UK ETS auction average with no free-allocation discount — pending HMRC's first published rates. Rules basis: Finance Act 2026 (enacted) + HMRC draft regulations, reviewed 4 July 2026. General information, not tax advice.