Warehouse Management System for 3PL: Run the Invoice Test

A warehouse management system (WMS) for 3PL work does three things an ordinary WMS does not: it records which client owns every unit, prices each client's activity from that client's own rate card, and shows each client only its own stock and orders. A 3PL stores and ships goods for other businesses, so ownership belongs in every record.

In practice that means every stock record carries client, SKU (stock-keeping unit, the item code), warehouse, bin, lot, status and quantity. Two clients may both use the code "TSHIRT-M". The system must treat them as two different items that can never be picked for each other's orders.

A rate card is the agreed price list for one client: what you charge for storage, for each handling activity and for each extra service. The system applies it to recorded movements, so the invoice comes from what happened on the floor, not from a spreadsheet kept beside it.

The system multiplies each client's recorded activity by that client's rate card, adds the lines, then adds GST. Pick and pack means collecting each order's items and packing them for dispatch. Below is our worked example for one client for one month. The rates are round numbers we chose for the arithmetic, not market rates. Replace them with your contract rates.

Working: 60 × 450 = 27,000; 40 × 100 = 4,000; 2,000 × 25 = 50,000; their sum is 81,000; 81,000 × 0.18 = 14,580. For a supply within one state, the 18% splits into ₹7,290 central tax and ₹7,290 state tax.

Most 3PL storage and handling charges attract 18% GST as of October 2026, except storage of agricultural produce, which is exempt. Supplies between states carry 18% IGST (Integrated GST, the central levy on interstate supplies). Storage and warehousing is service code 996729 in the CBIC scheme of classification of services, and the rate notification 11/2017, hosted on the GST Council's notification page, sets supporting services in transport at 9% central tax plus 9% state or union territory tax. The notification is amended often, so confirm the current rate and code with your tax adviser before you configure invoices.

E-invoicing adds a step. Businesses above ₹5 crore annual turnover must e-invoice B2B supplies, and each e-invoice carries an IRN (invoice reference number, the unique code the government's Invoice Registration Portal issues). Businesses at ₹10 crore or more must report each invoice within 30 days of its date, from 1 April 2025, as the e-invoice portal states.

E-way bills sit closer to the warehouse floor than invoices do. Under Rule 138 of the CGST Rules, a registered person who moves goods worth more than ₹50,000 in one consignment must generate an e-way bill before the vehicle leaves. That covers movements that are not sales, such as transfers between warehouses and returns. Rules for movement inside a state differ, so check the threshold for each state you operate in.

A 3PL dispatches and transfers its clients' goods every day. Ask each vendor to show a dispatch that produces the e-way bill details without retyping the invoice, and confirm with your tax adviser who must generate the bill for each flow: you, your client or the transporter.

Under-billing happens at the edges of the rate card, where work is real but nobody recorded it as billable. Four edges are the likeliest places in our view (our inference, not measured data):

• Storage basis. Per pallet per day, month-end count and monthly peak give different totals for identical stock. Agree one basis in the contract and configure that one.
• Unscanned extras. Relabelling, kitting (bundling items into one sellable set) and returns inspection happen on the floor. If no scan or entry creates a billable line, no invoice line exists.
• Late adjustments. A stock count that corrects quantities after the invoice went out changes what you should have billed for storage.
• Unversioned rates. A mid-year rate change applied to the whole year misprices earlier months.

Here is the cost of missing 5% of pick-and-pack lines in our example. Five per cent of 2,000 orders is 100 orders, and 100 × ₹25 is ₹2,500 a month, or ₹30,000 a year for one client. Across 10 clients that is ₹3,00,000 a year. The 5% is our assumption for illustration. Measure your own gap by comparing a month of invoices with system movements for one client.

Run six checks with your own SKU codes, rate cards and client names. We publish this page and sell warehouse software, so run the same checks on us. Checks 3, 5 and 6 fit inside our 15-day trial, using a sample month of receipts and picks. Checks 1, 2 and 4 depend on per-client rules that are built to order, so run them in a configured demo or during onboarding.

Can two clients use the same SKU code without their stock mixing?

Receive 10 units of one code for Client A and 10 for Client B. Create an order for Client A. Pass: the system picks only Client A's units and reports Client B's stock untouched. Fail: any path lets Client A's order draw on Client B's stock. At Arka Inventory, multi-warehouse stock is native; client ownership on every stock record is built to order on Salesforce.

Does it reproduce your invoice to the rupee?

Load one real client month and compare the system total with your hand-built invoice. Pass: identical total, with separate lines for storage, receiving and picking. Fail: any gap, or any step that needs a spreadsheet export to finish the invoice. At Arka Inventory, receipts, putaway, picks and packs are recorded natively and custom reports and dashboards can total them; per-client rate-card billing and the GST invoice are built to order on Salesforce.

Does the price change when you add a client, a user or a warehouse?

Ask for a written price for your planned size: clients, users and warehouses. Pass: one figure in writing. Fail: "it depends". Some vendors charge per extra warehouse, others per user, others per shipment. We price by plan and user, set out below.

Can a client see only its own stock and orders?

Create a test login for one client. Pass: it shows that client's stock, orders and status, and nothing from any other client. Fail: any other client's SKU, order or quantity is visible anywhere, including reports and search. At Arka Inventory, client-only logins and views are built to order on Salesforce, which supplies the identity and access controls they sit on. Inventory information can also be shared with partners through Salesforce community features.

Can you prove who changed a stock quantity, and when?

Pick one stock adjustment and trace it. Pass: within a minute you can show the user, time, reason and quantity before and after. Fail: the history cannot be shown. Our cycle counting guide sets out the count and adjustment rules behind this. Arka Inventory runs on Salesforce, which provides monitoring and auditing, so trace one of your own adjustments in the trial to confirm it shows what you need.

Do invoice figures reach your accounts without retyping?

Send one client invoice to your accounting system. Pass: the lines, and the IRN if you e-invoice, arrive in Tally or QuickBooks Online without re-keying. Fail: any manual entry of amounts or codes. We publish integrations with both Tally and QuickBooks Online; bring your e-invoicing set-up to the demo to confirm how the IRN is handled.

Which systems does a warehouse management system for 3PL need to connect to?

A 3PL rarely works from one system. Orders arrive from each client's online store or marketplace, goods leave with couriers, and invoices land in your accounts. Test these links on one client's data before you commit.

Ask the vendor to show three things. First, an order from that client's store or marketplace reaching the warehouse without retyping. Second, a courier label and tracking number going back to the client. Third, a stock level the client can read without calling you. Pass: all three run without manual entry. Fail: any step needs a spreadsheet or an email.

What types of warehouse management system for 3PL can you shortlist?

Most options fall into three groups. Use the table to pick the group, then run the six checks on two or three vendors inside it. The names are examples from published vendor lists, not endorsements, and we have not tested them.

Any group can pass or fail the invoice test, so treat the group as a starting point, not a verdict.

Cost depends on what the vendor counts: users, clients, warehouses or shipments. Ours is a yearly subscription by plan and user. As of October 2026 our listed prices are in US dollars and billed yearly.

For a 3PL, the plan decides what you can run. On the published plan list, sales orders and bin tracking sit in Enterprise, so a 3PL that runs client orders through storage bins should expect an Enterprise quote rather than the Basic or Advance price.

Ask for that quote in rupees, ask whether 18% GST is extra, and list your clients, users, warehouses and the custom billing and client-view work from checks 1, 2 and 4, so one written figure covers everything. Our cost guide for inventory software in India sets these figures beside other options.

Arka Inventory covers receiving, putaway, picking, packing and multi-warehouse stock natively, with sales orders and bin tracking on the Enterprise plan; per-client billing and client-only views are built to order on Salesforce. We are cloud inventory, warehouse, purchase and cost software built natively on Salesforce, and we build custom requirements.

Our warehouse management feature runs receiving, putaway into bins, picking and packing on barcodes, and Arka Inventory supports multiple warehouses on every plan. It suggests which items to pick and from which bin, picks earliest-expiring lots first for lot-tracked products and uses first-in, first-out (FIFO) picking for the rest. Our Salesforce inventory management guide explains how stock stays in sync with sales orders there.

Mankato Moving and Storage and YourWay / Owatonna Logistics run inventory and warehouse management on Arka Inventory. As of October 2026, we have more than 30 paying B2B customers and a 4.8 rating on Salesforce.

Standalone 3PL warehouse tools concentrate on warehouse and client-billing operations; we concentrate on inventory and operations inside Salesforce, so we fit best where your customer, order and stock data already sit there. Our warehouse management software buyer's checklist for India covers the wider requirements.

Onboarding takes a minimum of two weeks, depending on how ready your inventory, product and warehouse data are and how complex your business rules are. The trial runs 15 days with full access and no credit card, and access ends automatically when it does.

Next step: bring your rate card and one month of activity to a demo, and tell us which of checks 1, 2 and 4 you need built. Contact our sales team. Support is available Monday to Friday, 9 AM to 6 PM IST, at support@arkainventory.com or +91 93902 73833.