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Blog · Procurement and supply chain · Procurement

Suppliers per category: what the tail costs, and which of it to keep

How a procurement team counts active suppliers per category from the purchase ledger, values the long tail in transaction cost rather than spend, finds the suppliers with one order a year that a contracted supplier could cover, and separates the tail worth consolidating from the specialist suppliers the tail is hiding.

The short answerCount active suppliers per category from the ledger, then split them by spend and by order count. The tail is the suppliers with small spend and few orders; its cost is the transactions, onboarding and payments, not the spend. For each tail supplier, check whether a contracted supplier in the same category sells the same items. Those that do are consolidation candidates, valued at transaction cost saved; those that do not are specialists and stay, and the report says which is which.

A category has 312 active suppliers. Eleven of them account for 90 percent of spend. The other 301 account for the other 10 percent and for most of the invoices, the supplier records and the payment runs. Somewhere among them are forty specialists nobody can replace and 260 that a contracted supplier already covers. This guide sets out how the ledger tells them apart.

The measures

Per category:

Active suppliers = suppliers with a paid invoice in the trailing twelve months Tail = active suppliers below a stated spend and order count Tail cost = tail suppliers × transaction cost per supplier per year

Per tail supplier:

Overlap = share of its items also supplied by a contracted supplier in the category

The rows you need

  • Purchase ledger: supplier, category, item, date, amount, invoice.
  • Contracts: category, supplier, items or catalogue.
  • Supplier master: supplier, status.

Supplier identifiers only.

The split

Group Spend Orders Overlap Reading Action
Core High Many Contracted or should be Compliance
Tail, covered Low Few High Consolidate Route to the contracted supplier
Tail, specialist Low Few None Keep Nothing
Tail, unclear Low Few Partial Category manager decides Review

A worked example

One category, trailing twelve months. Transaction cost per supplier per year stated at $900.

Group Suppliers Spend Invoices Cost of the tail
Core 11 $8.4m 1,900
Tail, covered 214 $610,000 2,300 $193,000
Tail, specialist 38 $190,000 240
Tail, unclear 49 $140,000 410

Two hundred and fourteen suppliers whose items the core already sells, generating more invoices than the core does, at a stated cost that the consolidation removes. The thirty-eight specialists stay, named. The forty-nine unclear go to the category manager with the overlap shown.

The assertion

category spend = Σ core + Σ tail groups

And every active supplier is in exactly one group. A supplier in two categories is in each category's count separately and flagged, because that is often a category coding problem.

Where it goes wrong

Tail valued at spend. Small by definition; the argument fails. Value the transactions.

Specialists consolidated. The one supplier of a critical part is on the list because it is small. The overlap check is what keeps it off.

Inactive suppliers counted. The master has twice the active count. Use the ledger.

One transaction cost for all. A supplier paid by card costs less than one on purchase orders. Two rates, stated, if the difference matters.

Every quarter, per category

Mapped once, the ledger, the contracts and the master produce the groups, the overlap and the tail cost per category every quarter, with the specialists named. Covirage builds this from the exports as they are. The procurement page describes the setup, and the contract compliance guide covers the compliance measure that consolidation improves.

Questions people ask

What counts as an active supplier?

A supplier with at least one paid invoice in the trailing twelve months. Suppliers on the master with no activity are a separate list, for deactivation, and are not in the count.

How is the tail valued?

At the transaction cost per supplier per year: a stated figure for maintaining a supplier record, processing its invoices and making its payments, times the number of tail suppliers that could be consolidated. Not at their spend, which is small by definition and does not go away.

How do we know a contracted supplier could cover a tail supplier?

Item overlap: the tail supplier's items, by description or code, matched against the contracted supplier's catalogue or its invoiced items. High overlap is a candidate; none is a specialist. The match is shown and confirmed by the category manager.