Who should approve MRO and Class C consumables invoices

Executive Summary

MRO and Class C consumables spend gets approved the way low-dollar spend always does: fast, by whoever is closest to the requisition, against a purchase order rather than a contract. That routing works for catching a missing item. It does not work for catching a price that drifted off the catalog, a unit of measure that changed between order and invoice, or a substitution billed at the original part's price.

The fix is not a single approver. It is splitting the check by what each role can actually see. The requester confirms receipt.

The buyer or category owner confirms the price against the catalog or contract, not the PO. Accounts payable confirms the invoice matches what was approved. No one role holds all three, and collapsing them into one approver is exactly how a wrong unit price clears three cycles running.

Input costs on this category also move over time, which is exactly why approval has to check the current agreement and not memory of the old one. A catalog price that was correct months ago is a reasonable thing to have drifted since.

1. Who should hold approval authority for MRO invoices?

Three roles, not one: the requester or floor supervisor confirms the item arrived and matches what was ordered; the buyer or category owner confirms the unit price against the current catalog or contract; accounts payable confirms the invoice matches the approved purchase order before payment. Splitting the check this way means a wrong price has to pass two people looking at different things, not one person looking at all three at once and missing one.

A single-approver model collapses these three checks into one person's judgment on one screen. That person has the PO open, not the catalog, so they can confirm quantity and item but not price. The price gets approved by default.

Giving the buyer or category owner a standing role in the approval chain, even a light one, closes that gap. They are the person in the chain with reason to know what the current agreement says the part should cost.

Accounts payable's role is narrower than either of those: match the invoice to the PO that was already approved, not to the contract. Asking AP to also validate pricing against a catalog they do not own duplicates work and slows every invoice down.

A. Requester

Confirms the item physically arrived, in the quantity and condition ordered. This is a receiving check, not a pricing check, and should not be asked to do both.

B. Buyer or category owner

Confirms the unit price on the invoice against the current catalog or contract on file. This is the role positioned to catch a stale price or an unauthorized substitution.

C. Accounts payable

Matches the invoice to the approved purchase order and clears it for payment. AP should escalate a mismatch, not resolve a pricing question itself.

2. What does a dollar threshold change about who approves?

A dollar threshold decides how many roles touch the invoice, not whether pricing gets checked at all. Below a set line, a company can let the requester's approval stand alone, on the reasoning that the exposure of a single wrong line is too small to justify a second reviewer. Above it, the buyer or category owner review becomes mandatory before payment, because a wrong unit price repeated across a recurring order is no longer small.

The risk with Class C consumables is not the size of any one invoice. It is the recurrence. A small overcharge on a fastener ordered on a standing basis compounds the same way a much larger single error does, just more quietly.

A threshold set purely on invoice size misses this, because it treats a recurring low-dollar item the same as a genuine one-off. A threshold that instead looks at whether an item is a standing, repeat order catches more of the actual exposure.

Whatever line a company draws, it should be written down and applied consistently. An informal threshold that varies by who is asking defeats the purpose of having one.

3. How does unit of measure change what gets approved?

Unit of measure is a place a Class C invoice can diverge from the order without anyone approving that divergence. An order placed per box can be invoiced per unit, or a case size can change between the original agreement and the vendor's current packaging, and an approver checking only the total dollar amount has no way to see it. The check has to compare unit of measure explicitly, not just the line total.

This is a mechanical mismatch, not a pricing dispute. The unit price can be identical to what was agreed and the invoice can still be wrong, because the quantity basis changed underneath it.

Catching it requires the approver to look at the unit of measure field on the invoice against the unit of measure on the catalog or contract, as a separate step from checking the price itself. A total-dollar comparison alone will not surface this.

Because this drift type looks identical to a legitimate price change at the total-line level, it is worth naming as its own check rather than folding it into general price review.

• Case versus each: An order placed per case gets invoiced per individual unit, multiplying the effective charge without changing the unit price shown.
• Pack size change: A vendor repackages a larger box as a smaller one at the same box price, changing what the buyer actually receives per dollar.
• Weight versus count: An item priced by weight on the invoice against a quantity ordered by count leaves no clean way to verify the math without converting both.

4. Who should approve a substituted part?

A substitution should route back through the buyer or category owner before the invoice is approved, not through the requester alone. The requester can confirm a substitute part physically works. Only the buyer or category owner can confirm whether the substitute is priced correctly, because that requires knowing whether the substitute sits on the same contract or catalog line as the original part.

Substitution is where MRO approval most often breaks down, because the requester's sign-off is genuinely valid: the part that arrived does work. That is not the same question as whether it is billed at the right price.

A vendor substituting an equivalent part at the original part's contracted price is unremarkable. A vendor substituting a different part at a list price higher than the original's contracted price is a different transaction entirely, and it needs the same review a new item would get.

Routing substitutions through the same approver who reviews new items closes this gap without adding a new process step.

5. How should approval authority change as spend grows?

As MRO and Class C spend grows past what one buyer can review line by line, approval should shift from reviewing every invoice to reviewing exceptions against the catalog, with periodic sampling of the rest. The goal is not fewer eyes on the spend. It is putting the review effort where a price is most likely to have drifted, rather than spreading it evenly across many low-value lines.

At low volume, a buyer reviewing every MRO invoice against the catalog is realistic. Past a certain volume, it is not, and insisting on it just means the review happens less carefully or gets skipped.

Exception-based review changes the question from 'does every line match' to 'which lines moved since the last check.' A system that flags a price change from the prior invoice, or a new item not on the catalog, gives the buyer a shorter, more useful list to work through.

Periodic sampling of the invoices that did not flag anything covers what an exception rule cannot anticipate. Neither replaces the other.

How review effort should shift as MRO invoice volume grows.

6. What happens when no one owns MRO approval?

Without a named owner, MRO approval defaults to whoever is fastest, usually the requester, and pricing goes unchecked by default rather than by decision. This is not a failure of any one person. It is the predictable result of a category where every individual invoice is too small to justify a delay, so nobody is assigned the job of checking price against contract.

The absence of an assigned pricing check is easy to miss precisely because nothing about it looks broken. Invoices get paid, receiving is confirmed, the requester is satisfied the item showed up. The gap only shows up when someone compares the invoice history against the current catalog directly, which is not a step built into the normal approval flow.

Naming a category owner, even a part-time one, for MRO and Class C pricing changes this from a gap nobody is responsible for to a check somebody actually performs. It does not need to be a full-time role.

This is the same reason contract compliance work on other categories, like maintenance work orders or staffing rate cards, assigns a specific check to a specific role rather than leaving it implicit in the general approval process.

For the wider pattern this sits inside, start with the margin drift guide. See also accessorial charge audit: the surcharges nobody validates and rate card enforcement: why approved timesheets still produce wrong invoices.

7. Frequently Asked Questions (People Also Ask)

Does AP need to check pricing on MRO invoices?

No. AP's role is to match the invoice to the purchase order that was already approved. Pricing against the catalog or contract belongs to the buyer or category owner, who has the current agreement on file. Asking AP to do both duplicates work and slows down payment without adding a pricing check that is actually reliable.

Should every MRO invoice go through the same approval steps?

Not necessarily. A company can apply lighter review below a written dollar or recurrence threshold and require buyer or category owner sign-off above it. The line should be based on whether an item is a standing, repeat order, since recurring exposure compounds even when each invoice is small.

What is the difference between a receiving check and a pricing check?

A receiving check confirms the item arrived, in the right quantity and condition. A pricing check confirms the unit price and unit of measure on the invoice match the current catalog or contract. They require different reference points, which is why one approver rarely does both well.

Why does a substituted part need separate approval from the original item?

Because a substitute part can work physically and still be billed incorrectly. The requester can confirm the part functions but cannot confirm whether it sits on the same contract line as the original. Only the buyer or category owner can verify that the substitute is priced at the agreed rate rather than a higher list price.

Can a small company skip having a category owner for MRO?

A company can, but then no one is assigned to check pricing against the catalog, and that check tends not to happen on its own. The role does not need to be full-time. It needs to exist and be named, even as a partial responsibility added to an existing job.

How does unit of measure differ from a straightforward price increase?

A price increase changes the unit price itself. A unit of measure change alters the quantity basis, such as billing per unit what was ordered per case, so the unit price can look unchanged while the effective charge is not. Catching it requires comparing the unit of measure field directly, not just the total.

What should trigger a review of an MRO invoice at high volume?

A price change from the prior invoice for the same item, or a new item that does not appear on the catalog. Flagging on those two conditions lets a buyer focus review time on the lines most likely to have moved, instead of reviewing every line regardless of whether anything changed.

Who decides where the dollar threshold for MRO approval should sit?

That is a decision for the buyer or category owner together with finance, based on the company's own recurring order volume and risk tolerance. There is no fixed figure that applies across companies. The threshold should be documented and applied the same way every time, rather than varying by requester.