Sole sourcing

Sole sourcing means buying from the only supplier available for a particular requirement. This may arise from exclusive rights, a unique product or technical constraints, limiting the buyer's ability to switch suppliers.

The limitation may come from patent rights, proprietary technology, exclusive availability or compatibility with existing equipment. The buyer usually has less leverage to switch suppliers and may need to manage continuity through agreed stock, longer-term planning or redesign. The claim that no alternative exists should be assessed against the actual requirement.

For example, a machine may need a proprietary replacement component obtainable only from its maker. Choosing that source is different from selecting one of several capable suppliers. Single sourcing describes the latter decision; sole sourcing describes the absence of a viable alternative for the specified need.