3PL Migration Checklist: Moving Stock to a New 3PL Without Losing Orders

A 3PL migration checklist covers five things: your exit terms with the old provider, a stock count before and after the move, transport and booking in at the new site, a cutover plan for orders, and every system and carrier that points at the old warehouse. Done in that order, the pause in dispatch can be kept to a day or two, or avoided altogether. The orders that go missing in a migration are usually the ones caught between two systems on the day stock moves.

This guide is for brands that have already chosen a new provider. If you are still deciding when to move, read our guide on the best time to switch 3PL first.

The pain points

• The old 3PL's notice period is longer than you remembered, and the exit fees appear on the final invoice.

• Stock leaves one site with one count and arrives at the other with a lower one, and nobody can say where the gap went.

• Pallets sit in the new warehouse for days before they are booked in and sellable.

• Orders keep flowing to the old warehouse after the stock has gone.

• Returns and tracking emails still carry the old address and the old carrier.

Read the exit terms first

Start with your current contract, because it sets your earliest move date. Look for:

• The notice period and how it must be served, often in writing to a named contact.

• Minimum terms and any charge for leaving early.

• Exit or handling-out fees: per pallet, per carton or per unit charges for picking stock out and loading it.

• Account closure or data export charges.

• The lien clause. Many UK warehouse contracts, including those on UK Warehousing Association standard terms, let the warehouse hold goods until outstanding charges are paid. Settle every invoice before the collection date so your stock can leave.

Give notice in the way the contract says and get a written date for the final collection. Our guide to what a 3PL costs in the UK lists the lines that tend to appear on a final bill.

Count and reconcile the stock

The count is your only proof of what left the old site. Agree a full stock count with the old 3PL a few days before collection, and ask for the result by SKU, with batch and expiry dates where you track them.

• Compare the count with the old 3PL's system and your own records, and agree every difference in writing before the stock moves.

• Separate damaged, quarantined and returned stock that has not been graded. Decide whether it moves, gets written off or gets returned to you.

• Ask for a packing list per pallet that shows the SKUs and quantities on it.

• When the stock arrives, the new 3PL counts it on receipt. Compare that count line by line with the outbound count, and raise gaps with the haulier and the old 3PL straight away.

Transport and booking in at the new site

Book the haulier for a fixed collection slot at the old site and a delivery slot at the new one. Ask the new 3PL how many pallets it can receive a day and how long receipt takes before stock shows as available. Send it an advance shipping notice with every pallet's contents so it can plan labour and check the delivery. Our guide to the advance shipping notice explains what to include.

Stock on a lorry cannot be sold. A large catalogue usually moves in several loads, so plan which SKUs travel first.

Plan the cutover

Pick one of three approaches and write it down with dates:

• Hard switch with a short order pause. All stock moves in one go. You stop sending orders to the old site at a set time, the stock travels, and the new site starts once receipt is complete. Simple, with a dispatch pause of a day or more. Tell customers about the delay at checkout.

• Split by SKU. Slow sellers move first while the old site keeps shipping fast sellers. Orders route to whichever site holds the stock. This keeps dispatch running and needs careful routing for orders with items at both sites.

• Parallel running. Both sites hold stock for a few weeks. This gives the most cover and costs the most, because you pay storage twice.

Whichever you pick, set a time when the old 3PL stops accepting orders, and have it confirm in writing that every order sent before that time has shipped.

Update integrations, carriers and customers

• Store and marketplaces. Install the new 3PL's connector, assign products to its location and check order routing. In Shopify, a product cannot be removed from a location while it has unfulfilled orders there, so clear the old location's open orders first. Our guide to Shopify 3PL integration has a test plan. Repeat for Amazon, TikTok Shop and any wholesale channel.

• Carrier accounts. If you hold your own carrier accounts, update the collection address and service settings. If you use the new 3PL's rates, confirm the services match what you promise at checkout.

• Returns. Change the returns address on your website, return labels, packing slips and returns portal on the day the new site goes live.

• Customers. Add a delivery notice to the site for the pause, adjust delivery promises at checkout, and brief customer service on the dates.

• Suppliers. Send new delivery addresses and booking rules to every supplier with an inbound order due.

Our recommendation: count back from the notice period and move in a quiet month

1. Read the old contract and note the notice period, exit fees and lien clause.

2. Pick a move date in a quiet trading month, well clear of peak, and count back to the date you must serve notice.

3. Serve notice in writing and agree the final collection date.

4. Choose the cutover approach and share a dated plan with both 3PLs.

5. Connect and test the new integration before any stock moves.

6. Run the outbound count, settle invoices and book transport.

7. Send the ASN, receive and count at the new site, and reconcile line by line.

8. Switch order routing, returns addresses and carrier settings, then watch unfulfilled orders daily for two weeks.

The first month at the new site follows our guide to 3PL onboarding in the first 30 days. The pillar guide on how to choose a 3PL for ecommerce in the UK covers selection.

What waiting costs

The notice period is the clock. These figures are made up to show the method. A brand on a 90-day notice period decides in mid-August to move before Christmas. Notice served on 1 September ends on 30 November, which puts the stock on a lorry during the busiest weeks of the year. Served on 1 July, the same notice ends on 29 September and leaves October to settle in. Many 3PLs also stop onboarding new clients in the run-up to peak, so a late decision can mean another season at the site you wanted to leave.

People Also Ask

How long does it take to move to a new 3PL?

The notice period in your current contract usually sets the timeline, often one to three months. The physical move and booking in can take a few days to two weeks, depending on stock volume and the new site's receiving capacity.

Can I keep selling while stock moves between 3PLs?

Yes, with a split by SKU or parallel running. A hard switch usually needs a pause in dispatch of a day or more, which you announce at checkout and on your site.

Who pays to move stock between 3PLs?

Usually the brand. Expect handling-out fees from the old 3PL, transport costs, and receiving fees at the new site. Some new providers will discuss help with the move, so ask when you compare quotes.

Finding the right 3PL partner for your move

Logan, FulfilQ's advisor on the website, matches brands to verified providers by order volume, product type and region. Tell Logan what you ship, how much stock you hold and when your notice period ends, and you get a shortlist to ask about receiving capacity, migration support and go-live dates. Start at fulfilq.com and Ask Logan, or Submit an RFP and verified providers come back to you. You can also browse the full provider directory.