Moving a SKU to a New Supplier Without a Gap in the Middle

A supplier switch changes three numbers at once

When a SKU moves to a new supplier, the lead time, minimum order and unit cost usually all change together. Each one feeds a different part of the reorder: lead time sets how far ahead you have to buy, the minimum sets how much you have to buy, and the cost sets what the order is worth. Change one and forget the others, and the next suggestion is sized for a supplier you no longer use.

The risky part isn’t the switch date. It’s the overlap: the stretch between the last delivery from the old supplier and the first sellable stock from the new one. If the new source takes longer, the overlap is longer than any normal reorder gap, and the stock you hold has to carry the SKU through it.

The overlap arithmetic: what the last old order has to cover

The final order from the old supplier is a bridge. It has to last from today until the new supplier’s first order is on the shelf, plus a buffer for that first order arriving late.

bridging order = daily sales × (new supplier lead time + slip buffer) − on hand − already incoming

Two conditions apply. The old supplier has to deliver the bridge before your current stock runs out. And the cover is measured against the new supplier’s lead time, not the old one, because the next stock after the bridge comes from the new source.

That’s why the bridge is bigger than a normal reorder when the new lead time is longer. A normal reorder only has to cover until the old supplier’s next delivery. The bridge has to cover until a delivery from a supplier that’s slower, and that you haven’t tested yet. It’s the same demand, measured over a longer span. A long new lead time set against a short run of stock is exactly the case the buying table flags as items that “run out before a reorder can land”.

Run the handover as a dated sequence

The order of the steps matters, because each one changes the numbers the next one uses.

Day 0, while the product is still assigned to the old supplier, place the bridging order with it. Its cost, minimum and case size are still the right ones for that order.

Same day, set up the new supplier’s rules: Lead Time, Reorder Cycle, Min Stock Cover Days, and order minimums and maximums. In Assisty, the buying table’s suggested quantities use these automatically.

Then reassign the products to the new supplier, and update each moved variant’s overrides (next section). Assisty lets you assign products by vendor name or by saved rule conditions. If you use saved rules, check that none still points the product at the old supplier.

Day 1, draft the first PO from the new supplier. If you change the lead time through the assistant, it confirms that tomorrow’s reorder suggestions will use it. So draft the first PO once the suggestion reflects the new lead time, and check that the breakdown shows the new cover period before you create the order. If the first PO goes out later than Day 0, add those days to the bridge’s cover.

Last, confirm the bridge is counted. In the buying table, a suggestion is computed from “sales velocity, lead times, and incoming stock”, and its breakdown subtracts incoming from open POs. Check that the bridge order appears there. If it doesn’t, the table will suggest you order the bridge quantity a second time.

Keep the per-variant overrides in step with the move

Supplier settings cover most products. Where one product differs, Assisty lets you override it per variant: supplier SKU, cost, minimum order quantity and case quantity. These overrides are exactly the fields a switch tends to leave behind.

An old case quantity rounds the new suggestion to a pack size the new supplier doesn’t sell. An old minimum fails an order the new supplier would accept, or passes one it won’t. An old cost misprices every PO and the inventory value behind it; see stale unit costs for how that spreads. An old supplier SKU sends the new supplier a code it has never seen. See your SKU isn’t the supplier’s SKU.

Edit the four overrides in the same sitting you move the product, not as a cleanup for later.

What to check on the first PO from the new source

In Assisty, a PO created from a supplier is pre-filled with suggested quantities, the supplier’s tax and currency, and a delivery location. Read the first one from a new source line by line anyway:

• Quantity is rounded to the new case size and clears the new minimum.
• Currency and tax are the new supplier’s, not the old one’s.
• Cost per line matches the new quote.
• Delivery goes to the location that will receive and sell the stock.

Before the first order, get the unit price, minimum, lead time and a written dispatch commitment from the new supplier. After the first order, compare when it actually arrived with the quoted lead time, and update the supplier’s Lead Time if they differ. Treat one delivery as weak evidence, though. New accounts can get priority treatment, so a supplier’s real reliability tends to show up on later orders, once you’re just another customer.