Customs Audit Checklist: 15-Point Self-Assessment for UK Importers

A customs audit checklist for UK importers should cover five areas: tariff classification, customs valuation, origin and preference, procedures and reliefs, and documentation. Benchmarking shows 17% of UK import declarations contain errors. Work through the 15 checks below to find and correct those errors before HMRC finds them for you.

Each check is a concrete task you can complete with your own declaration data. For a fuller walkthrough of the whole process, see our customs audit checklist guide. Run the assessment at least once a year, and again after any change of broker, supplier base or product range.

Why should UK importers self-assess before HMRC does?

Customs clearance is provisional, not final. HMRC can assess underpaid duty for three years after import, and you can reclaim overpayments across the same window. Self-assessment turns that window to your advantage: errors you find first can be corrected on your terms, through voluntary disclosure or a duty reclaim, rather than through a post-clearance demand with penalties and interest attached.

Most declaration errors are systemic, not one-off. A wrong commodity code or a misread Incoterm repeats on every consignment it touches, so a single finding from this checklist often applies to hundreds of declaration lines.

Are your commodity codes classified correctly?

Classification drives your duty rate, preference eligibility and regulatory obligations, which makes it the first place HMRC looks. Checks one to three cover it.

1. Commodity code accuracy

• Review your top 20 commodity codes by import value and volume.
• Cross-check each code against the UK Trade Tariff, including the duty rate, VAT rate and any measures attached to it.
• Confirm the description, material composition and function of the goods match the selected code.
• Document who approved each code and when it was last reviewed.

2. Classification consistency

• Compare declarations across different months, sites and brokers.
• Confirm identical or similar products are classified under the same commodity code.
• Check for legacy or superseded codes still in use.
• Maintain a central classification database and require your brokers to use it.

3. BTI and ATaR coverage

• Identify your high-value and high-volume commodity codes.
• Confirm whether Advance Tariff Rulings (ATaR) or legacy Binding Tariff Information (BTI) decisions exist for these codes.
• Check ruling validity dates and conditions of use.
• Quote ruling references correctly on declarations and store them with your records.

Is your customs valuation method sound?

Valuation errors cut both ways: some importers underpay and build up exposure, others overpay and never notice. Checks four to six test your method and its inputs.

4. Transaction value methodology

• Confirm the primary method used is the transaction value of the goods.
• Verify the price basis (Incoterms, currency and invoice terms) is correctly reflected in the customs value.
• Where transaction value cannot be used, document the alternative valuation method and the justification for it.

5. Additions and deductions

Check whether each of the following is correctly treated in the customs value:

• Assists: tooling, design or materials supplied free or at reduced cost.
• Royalties and licence fees related to the imported goods.
• Commissions, noting that buying and selling commissions are treated differently.
• Transport, insurance and handling costs to the place of introduction into Great Britain.

Then confirm non-dutiable post-importation charges, such as inland freight and post-import installation, are excluded.

6. Related party transactions

• Identify imports from related companies or group entities.
• Confirm transfer pricing policies are documented and aligned with customs valuation rules.
• Check for transfer pricing adjustments and how they are treated for customs purposes.
• Retain evidence that prices are at arm’s length, such as benchmarking studies or comparables.

Are you claiming every origin preference you are entitled to?

Preferential duty rates under trade agreements are only worth what your documentation can prove. Checks seven to nine cover eligibility, evidence and the money you may have left behind.

7. Preference utilisation rate

• Identify imports that could qualify for preferential duty rates under free trade agreements.
• Calculate the percentage of eligible imports where preference is actually claimed.
• Investigate low utilisation rates and establish whether missing documentation or process gaps are the cause.

8. Origin documentation

• Verify that EUR.1 certificates, statements on origin and REX registrations are valid and complete.
• Check that supplier declarations contain all mandatory data and are signed and dated where required.
• Confirm retention of origin evidence for the statutory period.
• Make sure documents clearly link to the relevant consignments and commodity codes.

9. Retrospective preference claims

• Identify past declarations where preference was available but not claimed.
• Check whether valid origin evidence exists, or can still be obtained, for those consignments.
• Quantify the overpaid duty and consider a C285 repayment claim through CDS within HMRC’s three-year window.

Are your procedures, reliefs and import VAT correct?

Procedure codes and reliefs decide how much duty and import VAT you pay at the border. Checks 10 to 12 catch defaults, missed reliefs and reconciliation gaps.

10. Customs procedure codes

• Review the procedure codes used across your declarations.
• Confirm each code matches what actually happened to the goods: home use, warehousing, processing or re-import.
• Look for defaulted codes applied by brokers without a written instruction from you.

11. Reliefs and special procedures

• Assess whether returned goods relief, inward processing or outward processing could apply to your goods flows.
• For reliefs already used, confirm the conditions were met and the evidence is on file. Returned goods relief, for example, generally requires re-import within three years in an unaltered state.
• For reliefs missed at the time of import, assess whether a retrospective claim is still possible.

12. Import VAT and PVA reconciliation

• Reconcile your postponed VAT accounting (PVA) statements against the figures in your VAT returns.
• Match C79 certificates to declarations where import VAT was paid at the border.
• Investigate any declaration lines that appear on neither a PVA statement nor a C79.

Does your documentation stand up to scrutiny?

When HMRC opens an audit, it works from your declaration data and asks you to evidence it. Checks 13 to 15 test whether you could respond quickly and completely.

13. Declaration data review

• Request your Trader Records Extract (TRE) from HMRC: the line-level record of your CDS declarations that replaced the legacy MSS reports.
• Reconcile the TRE against your own import records and commercial invoices.
• Treat unexplained differences between the two as findings in their own right.

14. Record keeping and retention

• Confirm you hold the commercial invoice, transport documents and any origin or relief evidence for every declaration.
• Check records are retrievable by declaration reference (MRN), not scattered across mailboxes and broker portals.
• Retain customs records for at least four years, in line with HMRC guidance on archiving trade documents, and VAT records for six years. The retention requirement outlasts the three-year assessment window, so do not shred on the same clock.

15. Broker oversight and error handling

• Sample-check entries submitted by each broker against your written instructions.
• Track error rates by broker and feed the findings back to them.
• Keep a documented route for correcting errors: voluntary disclosure for underpayments and C285 reclaims for overpayments.

What should you do with your checklist results?

A completed self-assessment usually produces three lists: errors to disclose, overpayments to reclaim and processes to fix. Deal with all three.

• Fix the systemic cause first, whether that is a classification database, a valuation policy or a broker instruction template.
• Disclose underpayments to HMRC voluntarily. Coming forward first is consistently treated more favourably than waiting for an audit.
• Reclaim overpayments while the three-year window is open. Missed preferences, wrong duty rates and unclaimed reliefs are all recoverable.
• Re-run the 15 checks on a fixed schedule so new errors are caught within months, not years.

Working through 15 checks manually across thousands of declaration lines is the hard part. BorderAudit automates post-clearance customs audit: it retrieves your HMRC declaration data, runs classification, valuation, origin and relief checks across every line, and flags both risk and recoverable duty. You can check your eligibility for a free audit in a couple of minutes, and the self-assessment above becomes a report rather than a project.