How to Fill Out the Royal Mail Customs Declaration Form (CN22/CN23)

A Royal Mail customs declaration form is required on every parcel of goods you send from Great Britain to a destination outside the UK, and the form you use is either the CN22 or the CN23 depending on what’s inside. The CN22 covers shipments worth up to £270 and weighing up to 2 kg; anything above those limits, or containing more than three different types of item, needs the larger CN23. From 1 June 2026 the CN22 is being retired for almost all postal shipments, so the CN23 will apply regardless of value or weight.¹ You can complete either form by hand at a Post Office branch, print a blank copy from the Post Office website, or generate one automatically through Royal Mail’s Click & Drop platform at send.royalmail.com.

One boundary worth knowing before you start: if you’re posting from Northern Ireland to an EU country through Royal Mail or Parcelforce, no customs form is needed. Shipments from Northern Ireland to non-EU destinations still require one.² A letter containing only personal correspondence, and nothing with monetary value, also doesn’t need a declaration.

Choosing Between CN22 and CN23

The CN22 is a small adhesive label with room for a brief description, weight, value, and category of goods. Use it only if all three conditions apply: the total value is £270 or less, the parcel weighs 2 kg or less, and it contains no more than three different types of item.³

The CN23 is longer. It gives you more line items, a country-of-origin field for each entry, space for export licence information, and an EORI number field for business senders.¹ Use it whenever the parcel exceeds either the value or weight limit for a CN22, or when the item list runs past three categories.

After 1 June 2026 the choice largely disappears. Royal Mail and Parcelforce are moving to CN23-only for postal shipments, with combined labels the sole remaining exception.¹

Where to Get the Form

You have three routes:

Pick up a blank CN22 or CN23 at any Post Office branch and fill it in at the counter. Staff can point you to the right form if you’re not sure which applies.
Download a blank from the Post Office website and print it. The CN22 can be completed online before printing; the CN23 is a fillable PDF you print and complete by hand.⁴
Use Click & Drop at send.royalmail.com. The platform generates the declaration when you buy postage and transmits the electronic customs data to Royal Mail at the same time.¹

The digital route is the simplest because it handles the electronic pre-advice for you, which is now a separate requirement on top of the paper form.

Filling in Each Field

Write the entries in English, French, or the language of the destination country. The core fields are the same on both forms.

Sender name and full address, including postcode. On the CN22, if there’s no dedicated postcode field, put the postcode in the return address on the top left or back of the parcel.¹
Nature of goods. Tick one: Sale of Goods, Gift, Returned Goods, Commercial Sample, or Other. Only mark “Gift” if you’re sending as an individual, not as a business.³
Item description. Be specific. “Men’s cotton shirt” works. “Clothes,” “goods,” stock numbers, or design names do not. Put each different type of item on its own line.¹
Quantity, net weight, and value. For each line, list the number of units, the weight of the items themselves (not the packaging), and the value in GBP. Use the price paid, or fair market replacement cost for gifts. Do not include postage or packaging in the value. You cannot declare £0 or £0.01.¹
HS commodity code. A minimum six-digit code for each item (see below).
Country of origin. Where the item was manufactured or assembled.
Totals. Add up the quantity, weight, and value across all lines.
Signature and date. Sign and date the form on the day you post it. Your signature is what makes the declaration a legal document and confirms you accept liability for its accuracy.³

The CN23 adds a checkbox for export licence or certificate details (with a space to attach the licence in a marked envelope), an EORI number field, and additional line-item rows.¹ VAT-registered businesses posting zero-rated goods abroad should also ask for a Certificate of Posting at the counter as proof of export.

Finding the HS Commodity Code

Every line on the declaration needs a Harmonized System commodity code of at least six digits. This is the international classification customs officers use to identify what’s in the parcel and work out any duty or VAT owed. The UK government’s free lookup tool at gov.uk/trade-tariff lets you search by product type, material, or use, and shows the full code alongside applicable rates.⁵

Search using the broadest accurate description of the item. “Knitted cotton T-shirt” produces a better result than a brand name. If keyword searches don’t hit, browse the tool’s section index (textiles, electronics, food products, and so on). A wrong or missing code is one of the most common reasons parcels stall in customs.

Electronic Customs Data Is Now Required Too

A completed paper form on the outside of the parcel is no longer sufficient on its own. Royal Mail requires electronic customs pre-advice data and an S10 barcode for every international shipment, submitted alongside the CN23.⁶ Click & Drop, Pro Shipping, Royal Mail’s API, and several compliant third-party platforms transmit this data automatically when you create the label. If you’re posting in person with a handwritten form, ask branch staff how they submit the electronic data before you hand the parcel over. Skipping this step can trigger delays or a return.

Attaching the Form to the Parcel

Fix the declaration to the outside of the package, on the same side as the address label where possible, or on the back if there isn’t room. For a CN23, slot it into one of the transparent plastic wallets available free at Post Office branches, then stick the wallet to the parcel.¹ That keeps the form legible for customs officers and protects it from rain and rough handling. When you hand the parcel over, ask for a Certificate of Posting; you’ll need it if you ever have to file a compensation claim.

Mistakes That Get Parcels Delayed or Returned

Customs authorities will hold, return, or in some cases destroy a parcel if the declaration is incomplete or misleading. The errors Royal Mail flags most often:

Vague item descriptions like “clothes” or “gifts” instead of “women’s leather handbag” or “children’s plastic building blocks.”
Missing HS commodity codes. Every item needs at least six digits.
Fake or token values. Declaring £0.01 to help the recipient avoid import duties is one of the quickest ways to get a parcel seized, and some customs authorities auto-return anything with a suspiciously low declared value.¹
Missing sender address or postcode. Without a full return address, an overseas customs office has nowhere to send a rejected parcel back to.
An unsigned or undated form. The signature is what makes it a legal declaration.
No electronic pre-advice transmitted alongside a correctly filled paper form.⁶

Business senders have one more thing to watch: the EORI number. Commercial shipments leaving the UK must carry a GB-prefixed EORI on the declaration, and forgetting it is a recurring cause of stalled parcels.¹

Before you seal the parcel, it’s also worth checking Royal Mail’s prohibited and restricted items list. Aerosols, alcohol-based perfumes, standalone lithium batteries, bladed items, and fireworks cannot be sent internationally at all, and several other categories go only under strict packaging rules.⁷ An accurate customs form won’t rescue a parcel that shouldn’t have been posted in the first place.

1
Royal Mail. How to Send Internationally
2
Post Office. Customs Forms for Sending Abroad
3
Post Office. CN22 Customs Form Guide
4
Post Office. CN23 Customs Forms
5
GOV.UK. Trade Tariff: Look Up Commodity Codes, Duty and VAT Rates
6
Royal Mail. Electronic Customs Products and Solutions
7
Post Office. Prohibited and Restricted Items Mail