CN23 Troubleshooting Support

Same day

despatch

Free delivery available

on all orders*

Rated 5 stars

from verified users

Royal Mail

approved

Support from fully

qualified technicians

This guide explains the most common reasons parcels are delayed, returned, or rejected due to incorrect or incomplete CN23 customs declarations, and how to avoid them.

When a CN23 Is Required

A CN23 is required when:

  • Goods value is over £270, or
  • The service mandates CN23 (many tracked / Parcelforce services), or
  • An electronic customs declaration is required

CN23 is always used for parcels, not letters.

Common Reasons Items Are Returned

Most Common CN23 Failure Points:

  • ❌ Vague or generic descriptions
  • ❌ Missing itemised breakdown
  • ❌ Zero or unrealistic values
  • ❌ Missing HS / commodity codes
  • ❌ Missing country of origin per item
  • ❌ Incorrect Incoterms / delivery terms
  • ❌ Missing VAT / EORI where required
  • ❌ Weight/value mismatch
  • ❌ No commercial invoice attached
  • ❌ CN23 not signed or not attached externally

Detailed Troubleshooting & How to Fix

CN23 requires item-level detail, not a single summary.

❌ Unacceptable:

  • “Goods”
  • “Merchandise”
  • “Parts”
  • “Samples”
  • “Accessories”

✅ Required:

  • What the item is
  • What it’s made of (where relevant)
  • What it’s used for

Descriptions must allow customs to classify the goods without guessing.

Each different item must be listed separately on the CN23.

❌ Incorrect:

  • One line covering multiple products
✅ Correct:
  • Separate lines for each product type, quantity, and value

Totals must equal the declared parcel value.

HS codes are mandatory on CN23.

Requirements:

  • Minimum 6-digit HS code
  • Code must match the item description

❌ Common issues:

  • Leaving HS codes blank
  • Using a generic or incorrect code

Incorrect HS codes lead to mis-classification and delays.

Country of origin means where the goods were manufactured, not where they are shipped from.

❌ Incorrect:

  • Leaving blank
  • Listing the export country instead of manufacture

Each item must have its own country of origin.

A CN23 must be accompanied by a commercial invoice.

The invoice must include:

  • Seller and buyer details
  • Item descriptions
  • HS codes
  • Quantities and values
  • Currency
  • Country of origin
  • Delivery terms
  • Signature and date

❌ CN23 alone is often insufficient.

Declared data must match:

  • CN23
  • Shipping label
  • Commercial invoice

❌ Mismatches trigger automatic customs holds.

Required when sending:

  • Commercial goods
  • Business-to-business shipments
  • Goods to the EU or other regulated destinations

Common issues:

  • Missing EORI number
  • VAT number not supplied when required
  • Recipient details incomplete or inconsistent

Missing importer data can prevent customs clearance.

Delivery terms determine who pays duties and taxes.

Common terms:

  • DAP (Delivered At Place) – recipient pays charges
  • DDP (Delivered Duty Paid) – sender pays charges

❌ Missing or incorrect terms may cause clearance delays or refusal.

Requirements:

  • CN23 must be signed and dated
  • Must be placed in a documents pouch
  • Must be attached to the outside of the parcel

❌ Forms placed inside the parcel may not be seen by customs.