Bound a Last-Time Buy with Explicit Remaining-Demand Scenarios

A last-time-buy decision should identify what remaining requirement the proposed purchase covers, which supply already covers part of it and what uncertainty the authorized owner is accepting. Urgency does not make an unsupported lifetime quantity more reliable.

Use a last-buy scenario and approval record only after the exact discontinuance event and purchasing terms have been verified. This article provides an original planning method, not a notice for any actual item. No product-specific discontinuance notice, deadline, stock record or remaining-demand approval has been supplied.

Verify the notice before choosing a quantity

Obtain the manufacturer’s exact notice and the affected orderable identifiers, revisions or other applicability information. Preserve the original source, issue and any later revision. Match the buyer’s approved item to the covered scope through the responsible owner rather than assuming that a similar family name is sufficient.

Ask the purchasing channel to confirm what can actually be ordered under that notice and arrangement. Record stated ordering conditions, required acceptance events, relevant dates and unresolved exceptions from the real documents. A general status label, an old distributor listing and an accepted order are different evidence.

As a bounded manufacturer example, Texas Instruments’ product-life-cycle page distinguishes semiconductor statuses including not recommended for new designs, last time buy and obsolete. Its last-time-buy description concerns a product in the process of discontinuance; its obsolete description concerns one no longer in production. These are TI’s published semiconductor status categories, not another manufacturer’s policy or an exact item’s deadline or reseller availability.

Do not derive a purchasing window from that general example. The actual notice and order terms must settle the real opportunity. If those are missing, the useful output is an urgent evidence request, with quantity scenarios kept provisional.

Choose a remaining-requirement horizon

Define the interval covered by the decision, including its start, endpoint and intermediate need dates. The horizon should come from the authorized project or support requirement under review. It is not a forecast of product life, a warranty promise or a safe-storage duration.

List already approved outstanding project quantities separately from spare allowances and optional future uses. Give each a source and owner. A spare allowance may be an explicit risk decision without being a firm customer order; label it accordingly. Do not convert every installed unit into a replacement demand without an approved basis.

Keep mutually exclusive scenarios separate. A base case and a higher-demand alternative are alternative totals, not quantities to add together. State what changes between them and which assumption requires approval. No probability or service-level claim is necessary when the underlying data cannot support one.

Net existing supply exactly once

Fix a dated snapshot and one unit of measure. Eligible stock means the already-supported quantity applicable to these approved requirements, not every unit physically present. Exclude quantities unavailable for this scope under existing decisions; do not release quality holds or reassign other obligations through the calculation.

Use consistent demand and reservation treatment. If the remaining project demand includes reserved obligations, the eligible-stock input may include the units reserved to those same obligations. Subtract the supply once. Alternatively, if those matched pairs have already been removed from both demand and supply, calculate only the remainder. Do not keep full demand while excluding its reserved stock and then subtract the reservation again.

Applicable inbound supply must be an identified remaining commitment, not an order’s original quantity including receipts. Match it to the item’s scope and the relevant need dates. Late, unconfirmed or differently allocated supply belongs in an exception or alternate case. A purchase window closing soon does not make uncertain supply certain.

Use a scenario record that exposes the decision

Leave unsuitable or uncertain supply visible without counting it as coverage. Record purchase multiples or other commercial quantity constraints only when actually offered. Any amount above the scenario requirement needs its own explanation and authorization; a pack constraint does not create demand.

Hypothetical example: an 80-unit base case

Assume a fictional passive component and a day-1 snapshot. The authorized planning scope runs through day 180, with all intermediate due dates separately checked for the example. Open project requirements total 120 units. A separately approved spare allowance adds 10 units. The 120 and 10 are disjoint requirements; the allowance is not already embedded in the project total.

There are 20 eligible units available for this scope and 30 units of confirmed remaining inbound supply assumed applicable to the required dates. Those supply sets are disjoint. The existing 20 includes any units reserved to the 120 project obligations; those reservations are not deducted again. None of the inbound 30 has already been received into the 20.

The base-case candidate is 120 plus 10 minus 20 minus 30, or 80 units. This is a hypothetical net requirement, not an actual order recommendation. It does not establish that a supplier will accept 80 or that the goods will remain suitable for the whole horizon.

For a separate higher-demand case, suppose an optional project adds 25 units. Keeping all other assumptions fixed produces 105 units. The difference is 25, with the optional project clearly identified. The approver chooses whether that extra exposure is justified; the base and higher case must not be combined into 185 units.

If the 30-unit inbound commitment loses applicable timing, a sensitivity case without that supply becomes 110 units for the original base demand. That is a changed supply assumption, not an additional demand category. Resolve the timing where possible before selecting a commitment; do not add every adverse case together without explaining the combined conditions.

Obtain the non-arithmetic decisions

Ask the qualified owners whether the intended remaining uses and planned holding period are supported by the product-specific evidence. Keep unresolved suitability, storage and product-life questions as approval dependencies. This article provides no battery storage procedure, electrical guidance or extrapolated shelf-life figure.

Have the commercial owner review the actual commitment, amendment and cancellation terms. A last-buy label does not by itself establish refund restrictions or irrevocability. Where the real offer makes the decision difficult to reverse, disclose that specific condition with the chosen quantity rather than treating the arithmetic as sufficient approval.

Also record who bears the risk of unused quantity and what future demand would require a new decision. Do not assume resale, future repair demand, continued manufacturer support or an approved replacement product. Those assumptions can substantially alter the decision but remain unsupported until evidenced.

Close with the selected scenario, not a lifetime promise

Preserve the approved case, source versions, date, quantity limit and conditions required before placement. After any authorized order, verify its actual acknowledgement against that scope through the normal purchasing process. A sent request is not accepted supply.

The record is complete when it explains the finite requirement being funded and the uncertainty consciously accepted. It cannot guarantee uninterrupted lifetime availability. Any later approved replacement should trigger its own old/new demand-allocation review, rather than silently expanding this last-buy approval.

Frequently asked questions

Does a last-time-buy status tell me the final ordering date?

A general status description does not establish the exact purchasing deadline or acceptance conditions for your orderable item and channel. Obtain the actual notice and applicable terms. The TI example only distinguishes one semiconductor manufacturer’s status categories; it does not provide a current item-specific window.

Should I buy enough for the product’s entire expected life?

Only an authorized requirement and supported assumptions can define the quantity horizon. Do not invent replacement rates, shelf life or a lifetime support obligation. Separate firm remaining projects, approved allowances and optional scenarios, then have the responsible owner choose and accept a bounded exposure.

How do I avoid counting reserved stock incorrectly?

Keep demand and supply on the same basis. In the example, the 120 project units include their reserved obligations, and the eligible stock includes stock reserved to those obligations. That supply is deducted once. If matched reservations were already removed from both sides, work with the remainder instead.

Can a possible replacement reduce the last-buy quantity?

Only an existing authorized substitution decision for the affected uses can support that change in the demand basis. A supplier suggestion or similar specification does not establish equivalence. Keep the original requirement until its responsible owner changes it, and document any resulting cutover in a separate allocation record.