Switching 3PLs is a sequence of stages, and the order matters more than any single step: read your exit terms, test the new warehouse, move and count inventory, cut over your systems, settle transportation, then run both sites side by side for a short window. Orders break during a move when stages run out of sequence, not because any one stage is hard to do.
What comes first: notice and exit terms?
Read your current contract before anything else. You need the notice period, any exit or deactivation fees, the terms for releasing stock still on their shelves, and who holds your records. Give written notice once you have a realistic move date, because the notice clock starts when you send it, not when the last pallet leaves. Then get two things in writing from the outgoing team: the date of a final physical count, and how long they will keep handling trailing orders and questions after your volume moves.
How do you choose and test the new 3PL?
Shortlist on how the warehouse runs, not on the sales call: order accuracy, cutoff-to-ship time, inventory controls, and a full itemized invoice. Then test before you commit volume. A pilot on one SKU group, with written measures and a rollback path, shows you how the operation actually behaves under your orders. Sign only after the pilot passes, and write the first months of service levels into the contract itself.
How to structure that pilot, with the measures to set in advance, is covered in How do I test a new 3PL before moving all my volume?.
How does the inventory transfer work?
Two patterns work; pick one before freight is booked:
| Stage | What you do | What to watch |
|---|---|---|
| Count at origin | Wall-to-wall count before anything ships | Discrepancies resolved and signed off by both sides |
| Move | Book freight; slow movers first if you phase the move | Your peak season and launch calendar |
| Receive at destination | Count on receipt against the origin count | Who pays variance under the new contract |
A full count-and-move gives the cleanest baseline but needs either a short fulfillment pause or a buffer of pre-built orders. A phased transfer keeps you shipping throughout and needs more coordination. Either way, both warehouses must agree on one count before the second site starts fulfilling. What your contract says about exporting order and inventory records matters here too; see What happens to my data when I switch 3PLs?.
What happens to your systems and integrations?
List everywhere orders, inventory and returns flow: your storefront, each marketplace, your returns processor, your service tooling. Many storefronts link one fulfillment connection to each location, so cutover is a sequence, not a switch you flip twice. Run it in a low-order window, keep the old location active in your settings until trailing returns are done, and check that tracking numbers, packing slips and shipping-method names all render correctly before a customer sees them.
What happens to your parcel and freight rates?
Check who holds each carrier account before you sign anything new. If the contracts sit in the 3PL's name, your move ends those arrangements and you start from the new warehouse's shipping setup. If they are in your brand's name, the contracts travel with you: the warehouse changes and the transportation decision stays yours. That separation is the point. It keeps the decision about where goods are stored separate from the decision about how they ship, so choosing a warehouse never forces a rates decision on you. Confirm in writing who the carriers invoice and who can change a rate.
What do the first weeks after go-live look like?
Plan a short window where both sites run: open orders and trailing returns finish at the old site while new orders route to the new one. Watch four things daily in that window: order accuracy, on-time shipping, tracking data quality, and the first invoices against the quote. Fix what week one surfaces; a problem still appearing in week four is a process conversation, not a setup fix. Close out the old contract only after its final invoice and your final data export are both correct.
new3PL is an independent adviser that helps brands choose fulfillment partners and place parcel and freight transportation in the brand's own name. If you want a second pair of eyes on a move like this, it is one option to consider.
Frequently asked questions
How long does a 3PL switch take? It depends on your notice period, your inventory profile and how many systems connect to fulfillment. Build the sequence first, then set the date.
Can I switch during peak season? You can, but most brands schedule the move outside their heaviest weeks so a slow receiving dock never becomes a stockout.
What should be in writing before the move starts? The notice date, the final count, who holds each carrier account, the data export format and deadline, and how long the outgoing 3PL supports trailing orders.