How do I handle sales tax nexus created by a 3PL I just started using?

Using a 3PL creates physical nexus in that state the day your inventory arrives. The right time to handle registration is before the inventory ships. Here’s the sequence, and what to do if you’re already past that point.

Why the 3PL creates nexus

Your inventory stored in a third-party warehouse is your property, physically present in that state. This is physical nexus regardless of whether you own or lease the facility. States don’t require you to control the building, they require that your goods are there.

This applies to any 3PL arrangement: dedicated fulfillment companies (ShipBob, ShipMonk, Whiplash, Flexe), regional carriers with warehousing, or any facility where your inventory sits before shipping to customers.

If you know the 3PL arrangement in advance

The cleanest approach is to handle registration before or at the same time inventory ships.

Step 1: Confirm which state(s) the 3PL operates in.

Some 3PLs have multiple facilities in different states. Confirm exactly where your inventory will be stored, not just the 3PL’s headquarters. Ask your 3PL contact to specify the warehouse address(es) for your inventory.

Step 2: Register in those states before inventory arrives.

Registration processing times vary:

• Most states: 1–4 weeks
• California (CDTFA): 4–8 weeks
• Texas: often same-day or next-day
• A few states mail paper permits that add time beyond online registration

If your 3PL arrangement starts in 6 weeks, start registration now. If it starts in 3 weeks, registration in California may not process in time, plan accordingly.

Step 3: Configure your sales channels to collect in those states.

Update your Shopify nexus settings, WooCommerce tax configuration, or other platform before your inventory is in place. Tax collection should be live from the day your obligation starts.

Step 4: Set up filing for the new states.

Each new state will assign a filing frequency when it processes your registration (typically monthly for significant-volume sellers, quarterly or annual for smaller volumes). Calendar your first due dates.

If inventory is already there and you’re not registered

Your obligation started when your inventory arrived. You have uncollected tax liability for that gap period.

Short gap (1–3 months):

Register now. Calculate the uncollected tax for each month of the gap period using your actual sales data for that state. Remit the gap-period tax (plus applicable interest) with your first filing or as a separate voluntary payment. This direct-registration-and-catch-up approach works when the dollar amount and time period are manageable.

Longer gap (4+ months or significant dollar amounts):

A Voluntary Disclosure Agreement may be the better path. VDAs limit the lookback period (typically 3–4 years even if your exposure is longer), waive penalties, and close the liability with a defined resolution. For a 3PL arrangement that’s been running for a year or more without registration, the VDA path is worth evaluating before simply filing.

Multi-state 3PLs

If your 3PL operates facilities in multiple states, or if you shift to a new 3PL with warehouses in states you’re not in, audit your new physical nexus footprint against your current registration list. Growing businesses shifting to multi-state fulfillment often discover a gap between where inventory is and where they’re registered.

The audit is straightforward: list all states where inventory currently sits, compare against registered states, identify gaps.

The SST shortcut for SST member states

If your new 3PL is in an SST member state — Washington, Pennsylvania, Ohio, Michigan, Nevada, and 19 others, enrollment through a Certified Service Provider handles registration and ongoing filing at no charge. Registration in SST states through a CSP goes through the SST Central Registration System, which can be faster than state-direct registration for some states.

The nexus obligation and timing are the same. SST doesn’t grant a grace period or retroactively waive obligations. But if the 3PL state is SST, the ongoing compliance is simpler.