Three things set the earliest date you can leave your current 3PL, and none of them is in the new provider's hands: the notice deadline in your contract, how quickly the old warehouse packs out and releases your stock, and how long that stock spends on a truck. The new provider adds a gate of its own: the account has to be built and tested, and the warehouse ready to receive, before any stock ships. Most of the rest of a switch, from exporting data to connecting your store, fits inside the notice period if you start it early.

This guide follows the order a 3PL switch has to happen in. Read your contract first, get your data out while you still have access, build and test the new account while the notice period runs, then move the inventory and cut over on one date.

Start with the contract, not the new 3PL

Pull up the agreement you signed and find three things: when the current term ends, how far ahead of that date you have to give notice, and whether the term renews on its own. Most of the schedule follows from those three facts.

The arithmetic matters more than it looks. Take an agreement with 3-month terms that renew automatically and a 60-day notice window, which is how Simpl's own agreement works. If the term ends March 31, notice by January 30 ends service on March 31. Notice on February 1 misses the deadline, the agreement renews for another three months, and the earliest exit becomes June 30. Missing a notice date by a day can add a full term to your timeline, so work that date out before you do anything else.

While you have the contract open, note what it says about:

How notice has to be given. Email to your rep may not count if the agreement says written notice to a specific address.
Which charges keep running after you give notice, and until when. Your agreement decides whether storage stops or prorates once the stock leaves or runs to the end of the term, and which minimums still apply; don't assume either way.
Any early-termination or exit fee, and whether it still applies if you give proper notice.
Inventory release and removal: who packs the stock out, what they charge for it, how long they have to do it, and whether they'll release stock before the term ends if you ask.
Lien, hold or security-interest clauses that let the warehouse keep your goods while an invoice is open.
What happens to your account access, reports and order history after the last day.
Transition assistance, and whether it's billed.

If your relationship has already gone bad, the lien clause is the one to read twice. Under the Uniform Commercial Code, a warehouse has a lien on goods in its possession for storage and related charges, and after proper notice it can sell those goods to cover what it's owed. In practice that means a disputed invoice can hold your whole catalog. Pay what isn't in dispute, put the dispute in writing with the amounts and reasons, and get the release terms in writing before the truck is booked. Read your own agreement and, if real money is at stake, talk to a lawyer; this is general information, not legal advice.

Get your data out while you still have access

Do this the week you decide to leave, not the week before cutover: the data is easiest to get while you're still a customer in good standing, and you want the baseline before anyone has a reason to argue over it. Give one person on your side ownership of the data so nothing lives only in someone's inbox. You want:

Your SKU list with product weights and dimensions, barcodes and any kit or bundle definitions.
Current inventory by SKU, including lot or expiry data if you track it.
Open orders and anything held, backordered or partially shipped.
Order history for at least the last twelve months. Your new 3PL will quote from it, and it's your record if there's a dispute later.
Returns in progress and the return address printed on labels still in the wild.
Packaging specs, inserts and any special handling instructions you've built up over time.
Carrier account details, if you ship on your own accounts.

Then ask the old warehouse for a physical count of every SKU before packout, and compare it with the count in their system. That comparison is your baseline. Shortfalls found after the stock lands at the new warehouse are hard to pin on anyone.

Build the new account while the notice period runs

The notice window is dead time only if you let it be. Use it to pick the new 3PL and get the account built and tested, so the only thing left when the stock arrives is receiving.

When you're choosing, check the things that bite later rather than the feature list: the monthly minimum and what spend counts toward it (minimums vary a lot in what they include), receiving requirements and what a non-compliant carton costs, how the store integration handles inventory sync, and the provider's own exit terms. You're reading the next contract with the problems of this one fresh in your mind, which is the best time to read it.

How long account setup takes depends on the provider, so ask for its estimate in writing rather than assuming. Because setup can run while your stock is still at the old warehouse, it doesn't have to set the date, but it will if you start it late: stock arriving at a warehouse that isn't ready to receive it is the one delay in a switch that's entirely avoidable. Connect the store in test mode, keep the same SKU codes so order mapping is one-to-one, confirm packaging and inserts, set the returns address, and get the new provider to confirm in writing that it's ready to receive before you book the truck. Our onboarding timeline guide covers what tends to stretch this step.

Move the inventory

You have two ways to move stock, and the choice decides whether you ship through the switch or pause. Both assume the new account is live and tested first.

A single shipment is simpler and cheaper on storage. The old warehouse packs everything out, it goes on one truck, and the new warehouse receives it. The cost is a gap: stock on a truck or sitting in receiving can't ship from either warehouse, so your store stops fulfilling for the freight time plus the new provider's receiving window. For a brand shipping a few orders a day that's often acceptable, especially in a slow week.

A staged handover keeps you shipping. Leave enough stock at the old warehouse to cover orders for the freight time plus receiving, ship the rest, and route your next purchase order from your supplier straight to the new warehouse. The old warehouse keeps shipping your orders until the agreed cutover day; once the new warehouse has received the first shipment and confirmed counts, you cut over, every order from then on ships from the new side, and whatever is left at the old warehouse goes out as a final small transfer. The trade-off is a short stretch of split inventory, two sets of storage charges, and more care over which orders go where. This is a handover with one cutover date, not two providers fulfilling at once; the difference matters for the exclusivity question below.

Either way, decide what not to move. Freight on slow sellers costs you twice, once to move them and again to store them in a new building. Selling down, bundling or liquidating dead stock before the move is usually cheaper than paying to relocate it.

Budget for the move itself. Packout labor at the old warehouse, pallet or parcel freight between buildings, and receiving at the new one are each a line item, and some providers charge for all three. Label the cartons the way the new warehouse asks, typically one SKU per carton with a barcode on each unit and an inbound notice sent ahead, because a carton that doesn't meet them may have to be counted and relabeled by hand, which takes longer and can be billed as extra handling; the new provider's inbound requirements should tell you what that costs.

The cutover day

Pick one date, in a slow stretch, and well clear of any launch or sale. Changing warehouses in the weeks before your peak is the fastest way to turn a planned switch into an emergency; our pre-peak 3PL audit walks through how close is too close.

On the day, the sequence is: the old warehouse stops accepting new orders at an agreed cutoff and ships what's already in its queue, you switch the fulfillment location and ship-from address your store and marketplaces use, and the new warehouse takes orders from that point. Confirm that tracking numbers flow back to your store from the new side before you flip, because a day of orders with no tracking is what customers and marketplaces notice first. On marketplaces, the lever you control for certain is volume: clear as many open orders as you can through the old warehouse before its cutoff, so the new side's first day is small. If your marketplace account lets you lengthen handling time, setting it for cutover week gives the new warehouse room on new orders. Treat that as breathing room rather than protection, though: it doesn't change what you've already promised on orders in the queue, and a late first batch can still count against you.

What about running both providers side by side, each fulfilling live orders for a while? It's possible with some providers, but it rarely suits a small brand. You pay two sets of storage and possibly two minimums, you split stock that was already thin, and every order needs a rule about which warehouse ships it. It also isn't available everywhere: some provider agreements, including ours, make the provider your exclusive fulfillment provider once you're live. With those providers the overlap is the staged handover above, where the old warehouse ships until cutover day and not after, rather than an ongoing split.

Returns, the final invoice and the first month after

Returns don't know you've moved. Labels and portal addresses already issued point at the old warehouse, so agree with them how long they'll accept and forward returns and what that costs, or update your returns address on cutover and expect a few stragglers to need handling by hand.

Before packout, ask the old provider for a written close-out quote: what it will charge for packout labor, whether storage stops or prorates once the stock leaves or runs to the end of the term, which minimums still apply, and any removal or exit fee. When the final invoice arrives, reconcile it against that quote, the physical count you took and the contract terms you noted at the start, and keep paying the undisputed part while any dispute is open, for the lien reason above.

Thirty to sixty days in, check the new provider against the reasons you left: error rate on the first few hundred orders, receiving time on your first replenishment, whether the invoice reconciles to your orders without a call, and how fast your account contact answers. If the numbers aren't better than what you left, say so early while the relationship is new.

How long switching 3PLs actually takes

There's no fixed number, because the biggest items aren't in your control. The date comes from a handful of numbers you can get in writing:

The end of your current term, assuming you give notice before the deadline. This is often the longest wait, and nothing the new provider does shortens it. Miss the deadline and add a term.
The packout date the old warehouse agrees to, and how long packout takes. It may release stock before the term ends if you ask; your agreement and close-out quote tell you which charges keep running after the stock has left.
Freight time between the two buildings.
Receiving time at the new warehouse once the cartons arrive.
New-account setup and testing, which runs alongside the notice period and has to be finished before the stock ships. Start it late and it becomes the item that moves the date.

Say your term ends six weeks from today and you give notice this week, on time. You export your data now and build and test the new account over the next few weeks. You agree a packout date with the old warehouse, in the last week of the term or earlier if it will release stock sooner and the new side has confirmed it's ready. Your cutover date is then the packout date plus freight time plus the new warehouse's receiving window, and if you're using the staged handover, the old warehouse keeps shipping until that day. If you missed the notice window, the whole thing shifts by a term.

Switching to Simpl

If Simpl is the new provider, onboarding takes 5 to 7 days and receiving takes 1 to 3 days once your inventory reaches our Austin warehouse. Account setup runs while your stock is in transit: we connect your store and build your account, and receiving starts when the cartons arrive. The rule above still applies to us, though. Aim to have your store connected and tested before the truck leaves, so receiving is the only step left. There's no onboarding fee, and receiving is free when the shipment meets our inbound requirements. We plan one cutover date with you rather than running two warehouses: your current warehouse ships until that date, and we take every order from it. The overall switch date usually depends on the other side: your current 3PL's notice period, how quickly it releases and ships your inventory, and freight time to Austin. Our support article on how fast you can switch to Simpl has the details, and our agreement runs in 3-month terms that renew automatically, with written notice at least 60 days before the term ends to cancel, so read that the same way you'd read any other provider's terms.

Ready to talk about moving your fulfillment? Tell us about your store.

FAQ

Can I switch 3PLs during peak season?

You can, but don't if you have the choice. A gap in shipping costs the most when orders are at their highest, and every step of the move competes with peak volume at both warehouses. If the current provider is failing badly enough that staying is the bigger risk, use the staged handover, keep enough stock at the old warehouse to cover the move, and switch the week after your biggest sale rather than the week before.

What if my current 3PL won't release my inventory?

Find out why in writing. If it's an unpaid or disputed invoice, the warehouse may be relying on a lien over your goods, which the Uniform Commercial Code gives it for storage and related charges. Pay the undisputed amount, dispute the rest with reasons and figures, and ask for release terms in writing. If the provider has stopped responding or is winding down, move quickly: the longer stock sits, the more storage accrues against it. Talk to a lawyer when the amounts are material.

Should I run two 3PLs at the same time while switching?

For most small brands, no. Two providers each fulfilling live orders means double storage, possibly two minimums, split inventory and routing rules for every order, and some provider agreements, including ours, make the provider your exclusive fulfillment provider once you're live. A staged handover is different: the old warehouse ships until the cutover date and the new one takes over from it, so you keep shipping without running two operations. Plan a single cutover date and use the staged handover if you need to keep shipping through the move.

What does it cost to switch 3PLs?

The costs that surprise people are the old provider's final invoice (packout labor, whatever storage and minimums your agreement keeps charging after notice or after the stock has left, and any removal or exit fee), freight between warehouses, receiving charges at the new warehouse if it charges them, and a short stretch of double storage if you stage the move. Reading the exit terms before you give notice, and asking for a written close-out quote before packout, tells you most of this in advance.

How do I handle returns during a 3PL switch?

Returns already in transit are going to the old address. Agree with the old provider how long they'll accept and forward them and at what cost, update the returns address in your store and portal on cutover day, and expect stragglers for as long as return labels you've already issued are still out there; those get handled by hand.

How do I protect my marketplace metrics while switching?

Confirm tracking numbers flow from the new warehouse to your store and marketplaces before cutover, don't switch during a promotion, and clear as many open marketplace orders as you can through the old warehouse before its cutoff. If your marketplace account lets you lengthen handling time, setting it for cutover week gives the new warehouse room on new orders, but it's breathing room rather than protection: late shipments can still count against you. If you sell on several channels, moving them one at a time means two providers fulfilling live orders for a stretch, which only works where both agreements allow it. Where the new provider is your exclusive fulfillment provider once you're live, as Simpl is, every channel cuts over on the same date; if a marketplace needs extra care that day, pause that channel briefly rather than leaving its orders with the old warehouse.

How to Switch 3PLs: Notice, Inventory Move and Cutover, Step by Step