UK CBAM Deadlines 2026-2028: Every Date and What Triggers It

UK CBAM deadlines run from January 1, 2027, when the tax starts, to May 31, 2028, when the first return and payment fall due, and then move to a quarterly cycle. Every date on this page is traced to the Finance Act 2026, one of the five UK CBAM statutory instruments or HMRC guidance, and carries a status label as of October 12, 2026.

General Summary

The UK CBAM calendar holds 19 dated entries, 16 of them between October 2026 and February 2029, and the first one that binds an importer is January 1, 2027. From that day every business importing CBAM goods keeps import records, and a business at or above £50,000 of those goods becomes liable to register with HMRC.

Three dates carry the filing and cash risk. Registration for every person who triggers it during 2027 closes on January 31, 2028. The first return and payment, covering all of 2027, are due before the end of May 31, 2028. Quarterly accounting periods begin on January 1, 2028, and the first quarterly return is due on July 31, 2028.

How the tax itself works is covered in the UK CBAM guide; this page deals only with when each obligation falls, who it binds and which instrument fixes it.

What Is the UK CBAM Deadline Schedule?

The UK CBAM deadline schedule is a tax calendar built on accounting periods: a registered or registrable person makes a return and pays HMRC after each period ends. Paragraphs 6 and 7 of Schedule 17 to the Finance Act 2026 set the permanent rule: three-month accounting periods ending in March, June, September and December, with return and payment due before the end of the last working day of the second month after the period ends.

The Transitory Provision Regulations 2026 (SI 2026/830) modify that rule for the start-up phase. They create a single 12-month accounting period for 2027, fix three extended deadlines by calendar date, and replace the 30-day registration window with one date for everyone who triggers registration in 2027.

The six status labels used in the tables are defined below.

• Enacted: set by the Act or by a statutory instrument that has been made and takes effect on January 1, 2027.
• Enacted, approval pending: made, but still requiring a House of Commons resolution.
• HMRC guidance: stated by HMRC on gov.uk, not fixed in legislation.
• Draft: contained in a force of law notice that HMRC has published in draft.
• Expected: announced without a firm date.
• Calculated: worked out by cbamguide.com from an enacted rule.

Every UK CBAM Deadline in Order

UK CBAM deadlines fall into five groups: pre-commencement milestones, commencement, registration, returns and payments, and record retention. The table lists all 19 entries in date order with the legal source and status of each.

Statuses move. CBAM Brief, at EUR 199 a month, sends an email the day a CBAM certificate price, default value, CN code or deadline changes.

Deadlines Before Commencement

No importer filing falls before January 1, 2027, but one legislative date does. The rate and carbon price relief regulations (SI 2026/809) were made on July 13, 2026 under the made affirmative procedure. Section 157(10) of the Act provides that such an instrument ceases to have effect 28 days after it is made unless the House of Commons approves it, and section 157(13) leaves out of the count days on which the House is adjourned for more than 4 days.

Parliament's procedure record for the instrument lists a Delegated Legislation Committee debate on October 12, 2026 and the approval period ending on October 20, 2026. It records no approval resolution as of October 12, 2026, and HMRC's CBAM collection holds no rate, illustrative rate or default values notice on the same date.

Commencement and the First Accounting Period

January 1, 2027 is the commencement date: section 158(1) applies the tax to goods imported into the United Kingdom on or after that day. The first accounting period then runs for 12 months to December 31, 2027 under SI 2026/830, so 2027 contains no return and no payment.

The first sectoral rates apply from the same day. Section 149(3) builds each quarter's rate on UK ETS auction clearing prices from the preceding quarter, which makes October to December 2026 the quarter behind the first rate.

One emissions rule changes a year later. For goods imported before January 1, 2028, verified data may come from the year of import or the preceding calendar year; from that date it comes from the two calendar years preceding import. The year of production is allowed in both cases (SI 2026/995, reg 9).

Registration and Threshold Deadlines

Registration is triggered by £50,000 of CBAM goods, tested two ways, and the standard deadline is 30 days beginning with the trigger day. SI 2026/830 replaces those 30 days with January 31, 2028 for every person who triggers registration in 2027. A person who triggers it on January 1, 2028 is back on the standard rule and must register by January 30, 2028 (calculated from paragraph 2(4)).

HMRC's registration check guidance, published July 16, 2026, states that registration "will open by 1 January 2028", while HMRC's main CBAM collection page says it "will open on 1 January 2028". Neither page gives an earlier opening date. Both tests are explained step by step in the UK CBAM registration guide.

Return and Payment Deadlines

Return and payment share one deadline for each accounting period. SI 2026/830 fixes the first three by date: May 31, 2028 for 2027, July 31, 2028 for the first quarter of 2028 and September 29, 2028 for the second. From the third quarter of 2028 the permanent two-month rule applies.

That rule puts one published date in doubt. HMRC's policy summary lists November 30, 2028 for the third quarter. Paragraphs 6(3) and 7(2) set the deadline at "the last working day of the second month", and section 155(1) excludes from "working day" any day that is "a bank holiday in any part of the United Kingdom under the Banking and Financial Dealings Act 1971". Paragraph 2 of Schedule 1 to that Act makes November 30 a bank holiday in Scotland when it falls on a weekday.

November 30, 2028 is a Thursday, so on the statutory wording the last working day of the month is Wednesday, November 29, 2028. That date is cbamguide.com's calculation, not an HMRC statement, and HMRC had not addressed the difference as of October 12, 2026. Filing and paying by November 29 satisfies both readings. The February 28, 2029 date is unaffected: it is a Wednesday and matches HMRC's table.

The five consequences of a missed UK CBAM deadline are listed below.

• Late registration: a failure-to-notify penalty under Schedule 41 to the Finance Act 2008, and HMRC can register the person itself (Sch. 17 paras 2(7) and 34).
• Late return: the penalty regime in Schedule 24 to the Finance Act 2021 (Sch. 17 para 35).
• Late payment: the penalty regime in Schedule 26 to the Finance Act 2021 (Sch. 17 para 37), plus late payment interest under section 101 of the Finance Act 2009, applied to the tax from January 1, 2027 by SI 2026/994.
• Unreported change to registration details after 30 days: £500 fixed, plus £40 a day (Sch. 17 paras 4 and 38).
• Missing records: £500 (Sch. 17 para 39).

What goes into each return is covered in the UK CBAM reporting guide.

Record Retention Periods

Records are kept for 6 years beginning with the day after the accounting period ends (SI 2026/802, reg 6(2)), which puts the end of retention for 2027 records at December 31, 2033. The same period applies to verification reports (SI 2026/995, reg 16(3)) and to carbon price relief evidence (SI 2026/809, reg 15). Records tied to no accounting period run 6 years from creation.

Which UK CBAM Deadlines Apply to Your Business

Two facts decide which UK CBAM deadlines apply: whether the goods fall in one of five sectors, and whether their value reaches £50,000. Sector decides scope; value decides registration, returns and payment.

Deadlines by Sector

UK CBAM covers five sectors, and all five share one calendar. Section 143(3) of the Finance Act 2026 lists aluminium goods, cement, fertilisers, hydrogen, and iron and steel goods, and Schedule 16 sets the commodity codes.

Ceramics and glass are not in UK scope. HMRC's factsheet, updated November 28, 2025, states that the glass and ceramic sectors "will not be in scope of CBAM from 2027 as originally proposed (in December 2023)", and neither appears in Schedule 16. Electricity is not in Schedule 16 either.

Each sector gets its own quarterly rate on the same publication dates. Product-level detail sits on the UK CBAM sectors page.

Deadlines by Import Value

The £50,000 threshold decides whether the registration and return dates apply at all. Value means customs value (SI 2026/802, reg 3), and UK-origin and returned goods are left out of the count.

The look-back never reaches before January 1, 2027, because the tax applies only to goods imported from that date. A registered person files a return for every accounting period, including a nil return, until HMRC deregisters them.

UK CBAM Deadlines Compared With EU CBAM Deadlines

UK CBAM deadlines and EU CBAM deadlines share no filing date: the EU runs one annual declaration on September 30, while the UK runs one annual return for 2027 and then four quarterly returns a year. The merged calendar below lists both regimes in date order.

The EU side of this calendar, back to 2023, is set out in the CBAM timeline.

Where the Two Calendars Collide in 2027 and 2028

In 2027 the collision is in data, not filing. The UK asks for nothing but records, while the EU side of the business buys certificates from February 1 and files on September 30. Both regimes send the importer to its suppliers for emissions data in the same year.

In 2028 the collision is in dates. The UK return for April to June 2028 falls on September 29, one day before the EU declaration for 2027 imports.

One event would redraw both calendars. Section 156 of the Finance Act 2026 lets the Treasury exclude goods from a country with a linked emissions trading scheme, which is why UK and EU ETS linkage matters to every date above.

Which Deadline Comes First for a Dual-Market Importer?

September 30, 2027 comes first: the EU annual declaration for 2026 imports falls 8 months before the first UK return on May 31, 2028. A dual-market importer therefore completes a full EU filing cycle before filing anything with HMRC.

The UK obligation that starts first is quieter: import records begin on January 1, 2027, and the registration tests run from the same day. The EU dates are available as a filterable list with calendar export in the CBAM deadline tracker.

Frequently Asked Questions About UK CBAM Deadlines

When does UK CBAM start?

UK CBAM starts on January 1, 2027. Section 158(1) of the Finance Act 2026 applies the tax to goods imported into the United Kingdom on or after that date, and the five statutory instruments (SI 2026/802, 809, 830, 994 and 995) take effect the same day.

When is the UK CBAM registration window?

The window closes on January 31, 2028 for every person who triggers registration during 2027, and 30 days after the trigger day for anyone who triggers it later. HMRC guidance says registration will open by January 1, 2028, and no earlier opening date had been published as of October 12, 2026.

When is the first UK CBAM return due?

The first UK CBAM return is due before the end of May 31, 2028. It covers the single accounting period from January 1 to December 31, 2027, and payment is due on the same day (SI 2026/830, reg 2(3) and (4)).

Does UK CBAM have quarterly obligations like the EU?

Yes, from January 1, 2028. UK accounting periods become quarterly, each with its own return and payment. The EU's quarterly obligation is different in kind: a certificate holding check at each quarter-end, with one annual declaration. The UK CBAM vs EU CBAM comparison covers the structural differences.

How long must UK CBAM records be kept?

UK CBAM records are kept for 6 years, beginning with the day after the end of the accounting period they relate to. Records for 2027 are therefore kept until December 31, 2033. Failure to keep them carries a £500 penalty.

Does UK CBAM cover ceramics, glass or electricity?

No. Section 143(3) of the Finance Act 2026 names five kinds of goods: aluminium goods, cement, fertilisers, hydrogen, and iron and steel goods. Ceramics and glass were proposed in 2023 and dropped before legislation, and electricity is in EU scope only.