How much extra should you pay for a second supplier?

A second supplier improves continuity only if it can deliver the required product when needed. A name on an approved-vendor list is insufficient if tooling is unavailable, qualification has expired or the supplier has no spare capacity. Define the backup arrangement before comparing its price with the primary supplier's quote.

Specify the product, quality requirements, lead time, minimum order, production location and amount of demand the alternative can support. Ask whether that capacity is reserved or subject to availability. If both suppliers depend on the same upstream component or transport route, document that shared exposure. The alternative may reduce one kind of interruption while leaving another unchanged.

The finance decision is whether the additional cost buys a useful reduction in disruption exposure. That requires a delivery plan and evidence of capacity, as well as a unit-price comparison.

A dual-source plan can add more than a higher unit price. Qualification samples, audits, tooling, freight, smaller order sizes and separate receiving checks may all change spending. Some costs occur once, while others recur every order or every year. Keep their timing visible so management can compare the first year with an established arrangement.

Check whether shifting volume reduces discounts at the primary supplier. A secondary allocation that appears to cost only a few cents more can also move the remaining primary volume into a more expensive price band. Include that effect across all units affected by the purchasing change.

Retain the quotations, approved specifications and purchase commitments supporting the calculation. The IRS's recordkeeping guidance describes the need for source documents supporting purchases and expenses. Those same records give procurement and finance a common factual basis for reviewing what the second-source arrangement actually costs.

Assume a hypothetical business purchases 100,000 components per year. Its primary supplier charges $8 per component. A second supplier charges $8.80, and the proposed allocation sends it 20,000 components. The direct annual unit-price premium is $16,000. Suppose annual qualification maintenance adds $4,000 and split shipments add $3,000. The recurring premium is then $23,000 before any lost primary-supplier discount.

If initial tooling and qualification cost another $12,000, first-year incremental spending is $35,000. Later years may return to the $23,000 recurring amount, assuming the same volumes and terms. Separate those periods when presenting the decision; spreading the initial cost across several years can obscure the immediate cash requirement.

Now test volume changes. At lower demand, minimum purchases could force unwanted stock at the second supplier. At higher demand, the agreed backup capacity may cover a smaller fraction of production. A single annual premium is meaningful only alongside the demand and allocation assumptions that produce it.

Use operational scenarios to estimate what an interruption would do. A two-week delay might be absorbed by inventory. A six-week outage might stop production after the buffer runs out. A quality failure could also require rework or customer replacements. The loss depends on the specific failure and the time needed to restore acceptable supply.

Estimate lost contribution, unavoidable emergency spending and costs that can be avoided during the interruption. Do not treat every delayed sale as permanently lost revenue. Some customers may wait, while other orders may be canceled. Show the assumptions separately and ask the commercial team to support them.

If reliable probability evidence is unavailable, present break-even conditions rather than inventing a precise annual failure rate. Management can see how much avoided disruption would justify the premium and decide whether the protection is proportionate. Label any likelihood estimate as a planning assumption and explain who supplied it.

Suppose an illustrative interruption would cost $90,000 after existing inventory is used. If the second supplier can prevent only half of that loss, the modeled benefit per relevant interruption is $45,000. A $23,000 recurring annual premium would require roughly 0.51 such avoided-loss events per year to break even on that narrow expected-cost calculation. This does not mean the event will occur at that frequency.

The model may omit consequences management considers unacceptable, such as failure to meet a critical customer obligation. State those constraints explicitly instead of forcing them into an unsupported dollar estimate. Some decisions are made to meet a required continuity standard, with finance then comparing ways to satisfy it.

Check ramp time. A supplier that can eventually deliver the full volume may still need weeks to start. Qualification testing, tooling transfer and transport consume part of the recovery window. Reduce the modeled benefit to reflect that delay, and include any emergency premium required to accelerate output.

Review the second source using evidence of current capability. Confirm the approved specification, lead time, production capacity, contact chain and date of the last successful order. If the business rarely places an order, consider whether a small validation run is needed to keep the arrangement usable. Price that work in the continuity budget.

After a disruption, compare actual recovery with the planned scenario. Record which delays came from approval, production, transport or internal receiving. The result can support changes to inventory buffers, supplier allocation or contract terms. It may show that a more expensive supplier is useful, or that the bottleneck lies elsewhere.

Before renewal, update demand, supplier prices and shared dependencies. Management should approve a defined protection level for the next period. Leave procurement with an allocation schedule, a switching trigger and an owner who can authorize the move when the primary supplier misses the agreed condition.