Maverick spend is any purchase made outside the approved process: an unapproved supplier, no purchase order, a corporate card used for something it was never meant to cover. The purchase itself might be reasonable. The way it happened is the problem.
Tail spend is different. It’s the long list of suppliers who each get a small, infrequent order: a specialist part twice a year, a local vendor used once, a dozen sites all buying more or less the same paper and toner from different suppliers. No single transaction is worth chasing. Added up across hundreds of suppliers, it usually is.
The two overlap constantly. A one-off purchase from an unapproved supplier is both at once: small enough to be tail spend, off-process enough to be maverick spend. But they’re not the same problem, and they don’t take the same fix. Maverick spend responds to compliance controls and guided buying. Tail spend responds to consolidation and catalogues. Treat them as one thing and you’ll apply the wrong fix to at least half of what you find.
The Why: Why Does This Matter?
Neither one shows up in a review of the top twenty suppliers, which is exactly why both go unmanaged for years.
Off-contract purchases mean the pricing and terms procurement negotiated aren’t actually being used, which quietly erodes savings that were already claimed as won. A supplier base padded with hundreds of low-value vendors costs money in onboarding, invoicing, and admin long before you get to what’s actually being bought. And a category running twenty five or forty suppliers for broadly the same thing is a clear sign demand has never been aggregated, which means procurement has never negotiated from its real volume in that category.
None of it is dramatic on its own. It’s the kind of leakage that only becomes visible once someone goes looking for it.
The Where: Where Does This Spend Usually Hide?
Corporate cards
Purchases made outside procurement’s view entirely, often the first place maverick spend accumulates.
Split transactions
Purchases broken into smaller amounts to stay under an approval threshold, sometimes deliberate, often just habit.
Unapproved or duplicate suppliers
The same supplier entered under three slightly different names across systems, which also fragments spend data and hides true supplier concentration.
Categories with too many suppliers
Twenty five vendors for office supplies or forty for maintenance is rarely a sign of choice. It’s usually a sign nobody has ever compared notes across sites or business units.
Similar purchases under different descriptions
“Printer paper,” “A4 copy paper,” and “office printing paper” are likely the same requirement, recorded three ways, each reset back to looking like small, disconnected demand.
One-time suppliers
Vendors used once and never reviewed again, individually harmless, collectively a large share of the supplier base.
The How: How Do You Identify It?
Pull the data together. Purchase orders, invoices, requisitions, card statements, supplier records, and contract data, in one place, covering enough history to see patterns rather than isolated transactions.
Clean it before analysing it. Standardise supplier names, categories, and business units first. Until “ABC Technologies Ltd,” “ABC Tech,” and “ABC Technologies” are recognised as one supplier, every number downstream is wrong.
Check spend against approved contracts. Flag anything with no contract reference, an unapproved supplier, or terms that fall outside what was negotiated. A simple compliance rate, spend outside approved channels divided by total addressable spend, tracked by category rather than as one company-wide figure, usually surfaces where the real problem sits.
Look at fragmentation, not just value. A supplier billing a small amount for a component with no alternative source is strategic, not tail spend. Three hundred suppliers each billing a small amount for interchangeable goods is the opportunity. Value and strategic importance have to be weighed together.
Ask why, not just who. Maverick spend is rarely deliberate. More often the approved supplier didn’t stock what was needed, the requisition process was too slow, or nobody told the requisitioner which supplier to use. Fix the gap and a lot of the maverick spend resolves on its own.
Segment what you find. High-value maverick spend needs enforcement. Low-value maverick spend needs guided buying. Fragmented tail spend needs consolidation. Strategic tail spend needs to be left alone and managed deliberately, not swept into a cost-cutting exercise.
Reevaluate on a schedule. New suppliers get added, contracts lapse, habits drift. A tail spend review done once and never repeated is out of date within a year.
The Payoff
Maverick and tail spend both hide in the same place: outside the categories anyone is actively managing. Neither requires a new system to find, just clean data, a comparison against what was actually negotiated, and a willingness to look past the suppliers everyone already knows about. Get that visibility once, act on what it shows, and keep checking. That’s most of what separates spend that stays under control from spend that quietly grows back every year.
