Confirm why you are switching
Before you start a 3PL migration, be precise about what is not working. Write down the specific problems: shipping errors, late orders, inventory discrepancies, slow communication, billing disputes, a location that no longer matches your customers, or a lack of capabilities you now need, such as B2B or returns processing.
For each issue, gather evidence: order examples, dates, invoices, response times. This serves two purposes. It helps you evaluate whether a new provider will actually solve the problems, and it may give you leverage with your current provider on notice terms or final billing.
Also check whether any issues originate on your side. Inaccurate product data, poorly labeled inbound shipments or late promotion notices will cause problems with any provider. Fixing them before you move makes the new relationship start stronger.
Review your current contract
Your current agreement shapes the migration timeline and cost. Review it for:
- Term, renewal date and whether it auto-renews
- Required notice period for termination
- Minimum monthly commitments that continue during notice
- Termination fees or early exit penalties
- Inventory release terms, including fees and timelines for releasing your stock
- Liability and claims terms for inventory lost or damaged during release
- Final billing and how outstanding invoices must be settled
The inventory release terms deserve close attention. Some agreements allow the provider to hold inventory until all invoices are paid, so settle disputed charges early. Plan notice timing so you are not paying minimums at your old provider long after volume has moved.
Choose the right timing
Timing can make or break a migration. Avoid switching in the weeks leading up to your biggest sales period. For many brands that means completing the move well before the fourth-quarter holiday season, or waiting until after it.
A typical migration takes four to eight weeks from signed agreement to full cutover, depending on catalog size, integrations and how inventory moves. Work backward from a target cutover date, leaving buffer for receiving delays and fixes.
Also consider your supply calendar. If a large production run is about to ship, directing it to the new provider can reduce how much inventory needs to be transferred from the old one. That is often the cheapest and safest way to stock a new location.
Prepare your data and rules
Clean data is the foundation of a smooth switch. Prepare:
- A complete SKU list with barcodes, descriptions, dimensions, weights and any lot or expiration requirements
- Kit and bundle definitions with components and quantities
- Packaging rules by SKU and order type, including branded materials and inserts
- Channel-specific rules for marketplaces and wholesale accounts
- Shipping rules: service levels, carriers, signature and insurance thresholds
- Return rules: grading criteria and disposition instructions
Much of this may exist only in your old provider's system or in your team's heads. Export what you can from the old system early, before notice is given, and review it for accuracy. The new provider will use this information to configure its system, so errors here become errors in shipped orders.
Connect and test integrations
Integrations are where migrations most often go wrong. List every system that touches fulfillment: your storefront, each marketplace, EDI provider, returns app, subscription app, bundle app, ERP or inventory planning tool, and customer service platform.
For each one, confirm how it will connect to the new provider and what needs to change. Then test thoroughly before cutover. Place test orders through each channel, including orders with bundles, gift notes, multiple items and expedited shipping, and confirm they import correctly, are configured with the right packing rules, and post tracking back.
Pay attention to inventory sync. During the transition you may have stock in two places. Decide whether your storefront will show combined inventory across both providers or switch from one to the other at a set point, and configure locations accordingly.
Move inventory and cut over
There are two main ways to move inventory. A staged transition stocks the new provider with fresh inventory from suppliers or a partial transfer, starts routing orders there for those SKUs, then transfers the remainder. A hard cutover stops shipping at the old provider on a set date, transfers everything, and starts shipping from the new one once it is received.
Staged transitions carry less risk because orders keep flowing throughout. Hard cutovers are simpler to manage but create a window where available inventory is in transit.
Whichever you choose, get a full inventory report from the old provider before transfer, and compare it with what the new provider receives. Document discrepancies with photos and counts immediately so claims can be resolved. Ask the new provider to prioritize receiving transferred stock so it becomes available quickly.
Communicate with your team and customers
A migration touches more people than the operations lead. Brief your customer service team on the timeline, which orders ship from which provider during the transition, and how to look up order status in each system. Give them a short script for questions about delayed or split orders.
Tell your suppliers where to send new production, with the new receiving address, appointment process and labeling requirements, well before the next shipment leaves the factory. Update wholesale and retail accounts if ship-from addresses on their documents will change.
For customers, most migrations should be invisible. If a short delay is unavoidable, a brief note on your site or in order confirmations sets expectations and prevents a wave of support tickets.
The first weeks after switching
The first weeks with a new provider set the tone for the relationship. Monitor closely:
- Orders shipped on time against the agreed cutoff
- Mis-ships and customer complaints
- Inventory accuracy, especially for transferred stock
- Receiving turnaround on new inbound shipments
- Tracking and status updates flowing back to your storefront
- The first invoice, compared line by line with the rate card
Schedule a weekly check-in with your account contact for at least the first month to review exceptions and adjust rules. Small issues, such as an insert missing from one order type, are easy to fix early and become habits if left alone. After the first full month, compare results against the problems that prompted the switch to confirm the move delivered what you needed.
Frequently asked questions
How long does a 3PL migration take?
A typical 3PL migration takes four to eight weeks from signed agreement to full cutover, depending on SKU count, integrations and the inventory transfer approach.
Can my old 3PL hold my inventory?
Some contracts allow a provider to hold inventory until outstanding invoices are paid. Review release terms and settle disputed charges early to avoid delays.
What is the safest way to move inventory between 3PLs?
A staged transition, where the new provider is stocked first with fresh inventory or a partial transfer while the old provider keeps shipping, is usually safest because orders never stop.