Lot Numbers, SKUs, and Expiration Dates

A SKU and a lot number identify different things. A SKU identifies a particular product, while a lot number identifies a specific production batch of that product.

Imagine a company sells a 60-count bottle of Vitamin D3. Every bottle of that particular product may share the same SKU, but the warehouse could receive several production lots over time.

Those lots may also have different expiration dates.

A basic inventory count might show 4,000 units of the SKU. Lot-level inventory information goes deeper by distinguishing how those units are distributed among different production batches.

That distinction can be particularly important for supplements, nutraceuticals, packaged foods, cosmetics, and other products where dated or batch-specific inventory requires additional visibility.

How Lot and Expiration Tracking Works in 3PL Fulfillment

In a lot-controlled 3PL workflow, lot and expiration information is captured when inventory is received and maintained as the product moves through storage and fulfillment. The goal is to preserve enough inventory identity to distinguish batches, apply the appropriate rotation rules, and provide the level of traceability the brand requires.

The exact process depends on the warehouse, warehouse management system, product, and client requirements, but there are several important stages.

Receiving Inventory

Lot and expiration tracking begins when inventory enters the fulfillment operation.

When a shipment arrives, the 3PL needs enough information to identify what was received. For lot-controlled inventory, this may include the SKU, quantity, lot or batch information, expiration date, and other required product data.

Accurate receiving matters because this is where the warehouse establishes the inventory identity it needs to maintain downstream. If two lots of the same SKU arrive together but their lot numbers and expiration dates are not accurately distinguished during receiving, a simple total-unit count cannot recreate that missing lot-level information later.

Maintaining Inventory Records

Once inventory has been received, a warehouse management system, or WMS, can be used to maintain information about products stored in the facility.

For brands with lot-controlled inventory, knowing the total quantity of a SKU may not be enough. The operation may also need visibility into how many units belong to each lot and the expiration dates associated with that inventory.

The specific information available depends on the 3PL's systems and processes, which is why brands should understand the level of inventory visibility they actually require.

Applying Inventory Rotation Rules

As orders arrive, the warehouse needs rules for determining which eligible inventory should be picked.

For products without meaningful shelf-life considerations, receipt date may be sufficient for determining inventory rotation. For supplements and other dated products, the inventory that entered the warehouse first is not necessarily the inventory that expires first.

Picking, Shipping, and Outbound Records

Lot tracking can also extend into outbound fulfillment.

Once an order is released, the warehouse's inventory rules determine which eligible stock is selected. In operations that maintain lot-level outbound data, the lot associated with shipped inventory can remain connected to the fulfillment record.

That connection between receiving and outbound orders is what can make meaningful lot traceability possible. Brands that require this capability should verify exactly what information a prospective 3PL maintains and can report.

FIFO vs. FEFO

FIFO and FEFO are both inventory-rotation methods, but they prioritize inventory differently.

With FIFO, the inventory received first generally moves first.

With FEFO, expiration date determines priority. Eligible inventory with an earlier expiration date is generally selected before inventory that expires later.

For supplement brands, understanding that distinction is important when establishing inventory-rotation requirements.

Why Lot Tracking Matters Beyond Expiration Dates

Expiration management is only one reason lot tracking can matter. Lot-level visibility can also help brands investigate issues involving a particular production batch and understand what inventory remains in the warehouse.

That can become useful when:

• investigating a product or quality concern
• identifying inventory associated with a specific production run
• managing aging inventory
• determining what remains from a particular lot
• reviewing inventory before replenishment decisions
• responding to a manufacturer or supplier issue
• determining where affected inventory may have moved

Inventory management can also become more complicated as a brand adds sales channels. The same SKU may eventually move through ecommerce, subscriptions, marketplaces, wholesale accounts, and retail distribution.

At that point, the question is no longer simply, "How many units do we have?" A brand may also need to understand which inventory it has, which lots those units belong to, and where particular inventory has gone.

Managing Inventory That Is Getting Close to Expiration

There is no single expiration-management rule that works for every supplement brand. The appropriate process depends on the product, the brand's requirements, its sales channels, and applicable shelf-life expectations.

A brand may need to establish:

• how much remaining shelf life a product should have before it ships
• whether different sales channels have different requirements
• when aging inventory should be reviewed
• how short-dated inventory should be handled
• when inventory should be placed on hold
• what should happen to inventory that is no longer eligible to ship

These decisions are easier to address before short-dated inventory becomes an immediate problem.

The important distinction is that "supplement fulfillment" can mean different things from one provider to another. The actual warehouse process needs to fit the product and the brand's requirements.

What Happens If There Is a Problem With One Lot?

Lot traceability can make it easier to investigate inventory associated with a specific production batch.

Consider a hypothetical example. A supplement brand learns that there may be an issue involving Lot ABC123.

Those questions illustrate why lot tracking involves more than reading a code printed on a bottle. The real operational value comes from maintaining that lot identity as inventory moves through the fulfillment process.

If that level of traceability is important to your business, confirm what a prospective 3PL's system can identify and report. A warehouse should not be assumed to offer a particular recall, hold, or traceability capability simply because it stores supplements.

Questions to Ask a Supplement 3PL

When comparing fulfillment providers, detailed operational questions can tell you much more than simply asking whether they "handle supplements."

Consider asking:

1. How are lot numbers captured when inventory is received?
2. How are expiration dates recorded and maintained?
3. Can inventory be viewed by SKU, lot, and expiration date?
4. What inventory-rotation methods can you support?
5. How are minimum remaining shelf-life requirements communicated and applied?
6. How is aging or short-dated inventory identified?
7. What information can you provide if we need to investigate a specific lot?
8. How are affected or ineligible lots placed on hold or otherwise controlled?

If your company uses subscriptions, kits, wholesale distribution, Amazon, or other sales channels, discuss those workflows as well.

A useful fulfillment conversation should get specific about your products and operating requirements rather than trying to fit every brand into the same process.

Choosing a 3PL for Supplement Fulfillment

Lot and expiration management are only part of supplement fulfillment. Storage conditions, receiving, inventory visibility, ecommerce and B2B order requirements, kitting, returns, and communication all need to work together.

At Square1, our supplement and nutraceutical fulfillment services are supported by broader specialty fulfillment and warehouse services from our Springfield, Missouri operation.

The right fit starts with the product itself. What needs to be stored? What information needs to follow the inventory? Where are orders going? What storage, handling, shelf-life, and reporting requirements apply?

Those answers help determine whether a 3PL's actual capabilities fit the operation rather than simply checking a "supplement fulfillment" box.