uk Travel, documents & being abroad

What to do if…
you are asked for a customs reference number and cannot find the confirmation

Produced and maintained by PanicStation.org Published: 4 May 2026 Last reviewed: 17 July 2026 Editorial policy UK guide

Short answer

Pause before paying or sending documents, and verify who is asking and exactly which “reference number” they mean. Use the safest identifier you already have, such as tracking, waybill, barcode, receipt, or broker case reference, to get the correct customs reference re-sent or confirmed.

Do not do these things

Do not click payment links in unexpected texts or emails about customs charges until you have checked through an official route you found yourself.
Do not send photos of your passport, driving licence, bank card, or full personal documents to an unverified email address.
Do not guess a reference number or reuse one from a different shipment.
Do not assume a tracking number, invoice number, waybill number, MRN, CN22, CN23, CP72, or carrier clearance reference are all the same thing.
Do not delete receipts, screenshots, emails, label downloads, or portal messages while you are trying to recover the reference.

What to do now

Ask what kind of reference they need.
Ask: “Do you need an MRN, a carrier clearance reference, a tracking or waybill number, or the barcode or reference from a CN22, CN23, or CP72 customs form?” Ask them to describe what it should look like, including any letters, numbers, barcode, or label name.
Verify the request before you share anything.
Go to the carrier, courier, broker, or postal service through an official website, app, account, phone number, or branch route you found yourself. Check the shipment using the tracking number or waybill. If the request only appears in an unexpected text or email, treat it as unverified until you confirm it independently.
Search for the missing confirmation in the most likely places.
Search your email, spam, deleted items, downloads, screenshots, and shipping account for: MRN, customs, declaration, duty, VAT, clearance, CN22, CN23, CP72, barcode, label, waybill, the sender or retailer name, and the tracking number.
If this is a parcel or express shipment, ask the carrier to re-send or identify the request.
Give the carrier the tracking number or waybill, recipient name and address, and sender or retailer name. Ask them to re-send the customs or duty notification, or to tell you which exact identifier they need you to provide.
If this is a Post Office or Royal Mail customs form, look for the form reference, barcode, or downloaded documents.
The Post Office customs form process can create a unique reference or barcode to keep safe and show in branch. If you bought international postage online, check the order, label purchase, document download, or “view your documents” area for the CN22 or CN23 form. If you used a branch or online customs tool and cannot retrieve it, ask the service you used what they can locate from your receipt, posting proof, tracking number, or barcode.
If a broker or agent filed the declaration, ask them for the MRN or the reference they want you to quote.
Do not try to recreate the customs declaration reference yourself. Tell the broker or agent you cannot retrieve the confirmation and ask for the MRN, their case reference, and the exact wording to give to the carrier.
If you submitted a UK Customs Declaration Service declaration yourself, use your CDS route.
If HMRC has asked for documents or sent a query through the Customs Declaration Service, use your CDS access and Government Gateway route to check messages or upload documents. If a software provider or agent submitted the declaration, contact them instead.
Keep a short record while you sort it out.
Write down who asked, when they asked, the channel they used, the exact words they used, and any case, tracking, waybill, barcode, or receipt number. Screenshot genuine portal pages so you do not have to search again.

What can wait

You do not need to decide now whether to dispute charges, complain, or change how you ship in future.
You do not need to rebuild the whole shipment history before making contact.
You do not need to send extra identity documents unless a verified official, carrier, broker, or postal process specifically asks for them.
You do not need to know every customs term before asking which reference they mean.

Important reassurance

This is a common kind of mix-up because customs references, carrier references, barcodes, labels, tracking numbers, and broker case numbers can sit in different systems. A verified carrier, postal service, broker, or agent can often work from the tracking number, waybill, receipt, barcode, or recipient details.

Scope note

These are first steps only: verify the request, recover or identify the right reference, and avoid unsafe payment links or unnecessary document sharing. Later decisions about disputes, appeals, complex customs declarations, or business importing and exporting may need help from the carrier, broker, agent, HMRC route, or a customs specialist.

Important note

This is general information, not legal advice, customs brokerage advice, financial advice, or professional advice. What counts as a “customs declaration reference number” depends on whether this is a postal customs form, carrier clearance process, broker-managed declaration, or formal Customs Declaration Service declaration.

Additional Resources

About this guide

This guide was produced and is maintained by PanicStation.org using its published editorial process. Official and specialist sources are checked where relevant, and AI-assisted tools may be used for drafting, organisation, and consistency checks. The site operator remains responsible for publication, revision, and removal decisions.

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