The UK Business Guide to Tamper Evident Bags in 2026

If you're shipping anything valuable, sensitive or regulated, you've probably already wondered whether standard polythene mailers are enough. They're not — and tamper evident bags have quickly moved from a "nice to have" to a basic operational requirement for thousands of UK businesses.

What actually makes a bag "tamper evident"?

The defining feature is a permanent, single-use security seal that visibly destroys itself the moment it's opened. Unlike standard self-seal mailers, you cannot peel a tamper evident closure open and re-seal it without leaving an obvious mark — typically a "VOID" message, broken adhesive pattern or torn substrate.

Our Tamper Evident Bags use a high-tack permanent adhesive combined with a numbered sequential serial along the top — so every bag is uniquely traceable from the warehouse to the recipient.

Who actually needs them?

• Pharmacies and dispensaries — required for posted prescription medication and controlled cosmetic products.
• Cash-in-transit and retail banking — daily takings, coin bags and float deliveries.
• Evidence handling — legal practices, insurance investigators and security firms.
• High-value e-commerce — jewellery, electronics, watches and collectibles where chargeback fraud is a real cost.
• Subscription boxes with regulated contents — CBD, vitamins, supplements.

Choosing the right size and grade

The two questions to answer first are "what's going inside?" and "who needs to see the serial?". For internal cash handling you typically want a smaller A5/A4 footprint with a clear write-on panel. For e-commerce dispatch, A4 and larger gives room for a packing slip alongside the product.

Where they pay for themselves

The cost-per-bag is genuinely tiny once you're ordering by the case — usually a few pence each at volume. The first time you successfully defend a "didn't arrive" or "arrived empty" chargeback, you've already paid for a year's supply.

Pair them with the right outer packaging

Tamper evident bags are typically the inner security layer. For the outer parcel, most operators pair them with strong corrugated boxes or — for flat, low-bulk items — a grade-A polythene mailer.

Quick checklist before you order

• Confirm the largest item you'll ever post — and add 30mm headroom for the seal.
• Decide whether you need a write-on panel for batch numbers or recipient details.
• Order at least one tier above your current monthly usage — pricing breaks at 10+ packs and 25+ packs are significant.

Browse the full range of Tamper Evident Bags, or get in touch with the team if you'd like a sample pack before committing to a case.