Guaranteed maximum price contracts, explained for commercial owners

A developer we talked with last year had signed a guaranteed maximum price contract on a retail shell near the Borderland and assumed the word "guaranteed" meant he was done worrying about cost. Nine months in, he was staring at a stack of change orders and could not tell which ones were legitimately his and which the contractor should have eaten. Nobody had defined the contingency rules. Nobody had spelled out what the guaranteed maximum actually covered. The number that was supposed to protect him had quietly become a source of arguments.

That is the trap with a guaranteed maximum price contract, usually shortened to GMP and sometimes written as not-to-exceed. It sounds like the safe choice, and it can be a very good one. But it is only as strong as the scope, the assumptions, and the contract language behind it. Here is how it actually works, and where owners in El Paso and Las Cruces get caught.

What the guaranteed maximum actually covers

A GMP is a cost-type contract. The contractor is paid for actual costs plus a fixed fee, but the total is capped at a ceiling price. If the real costs land under that ceiling, you generally do not pay the difference. If they run over because the contractor set the number too low, the contractor absorbs the overage, not you.

On commercial work, that fee usually runs 3 to 8 percent of cost, either a fixed dollar amount or a percentage. Unlike a lump-sum bid, where the fee is buried inside one total price you never see broken out, the GMP fee is normally negotiated in the open. You know what the contractor is making.

The guaranteed maximum is built from a schedule of values, a line-by-line breakdown of the work, not a single guessed number. That detail is what makes the ceiling defensible. A GMP set without an accurate schedule of values is just a hopeful number waiting to fail.

Contingency and allowance are not the same thing

This is where owners get confused, and where budgets quietly leak. Contingency and allowance are both placeholders for cost you cannot fully pin down yet, but they behave very differently.

Contingency is a percentage-based safety net for cost growth nobody can itemize at signing. A GMP typically carries two separate layers:

• A GC contingency of roughly 2 to 5 percent of construction cost. This covers buyout gaps, scope gaps, productivity problems, and subcontractor issues. The contractor draws on it to keep the job whole.
• An owner's contingency of roughly 5 to 10 percent. This funds owner-initiated additions, design changes, and truly unforeseen conditions, like undocumented caliche that fights every foundation out here.

Who controls each layer is a core negotiating point. Owners usually want to control both, because whoever holds the contingency effectively decides how freely it gets spent.

Allowance is different. An allowance is a specific dollar figure held for a known scope item that has not been finally selected or priced, like a light fixture package or a flooring product. Contingency covers the unknown. An allowance reserves a spot for a known item at an estimated cost until the real number comes in.

Open-book accounting is the whole point

The defining feature of a GMP is that the books are open. The contractor keeps detailed cost records, invoices, purchase orders, labor costs, and you have the right to audit them. You are not taking a total price on faith. You can see where the money went.

Lump-sum contracts do not work this way. There, you see one price and nothing behind it. The contractor's margin and buyout are their business. With a GMP, that transparency is contractual, and it is the reason the model builds trust on longer or more complex jobs.

The trade-off is administrative burden. All that record-keeping and the owner's audit rights add real cost and effort to the project. It is a fair price for transparency, but it is not free, and a serious contractor will tell you that up front.

How savings get handled

If the job finishes under the guaranteed maximum, that unused budget does not vanish and it is not automatically the contractor's. By default, savings from cost underruns return to the owner. You keep what you did not spend.

Many GMP contracts add a shared-savings clause that splits the unused budget between owner and contractor on an agreed percentage. That split matters more than it looks. It gives the contractor a direct reason to finish faster and under budget, and it offsets some of the overrun risk they carry. Without a shared-savings clause, all the savings default back to you, and the contractor's only incentive is to avoid going over. Neither approach is wrong. Just know which one your contract uses before you sign.

How change orders interact with the ceiling

Change orders and the guaranteed maximum interact asymmetrically, and this is the single most important thing to understand. The ceiling can only go up through a formal change order, and only for one of three reasons:

1. Owner-added scope, meaning you or your tenant chose to add or upgrade something.
2. A design change after the GMP was set.
3. A genuinely unforeseen condition nobody could price at signing.

Cost growth from the contractor's estimating errors, omissions, or slow production does not raise the ceiling. That risk sits with them. This is the protection you are paying for, and it is worth reading the change order language carefully to confirm it says exactly that. A vague clause here is how a "guaranteed" number stops being guaranteed.

Where owners get surprised

A GMP is not automatically safer than a lump-sum contract. Its risk points are specific and predictable:

• Undefined scope. A ceiling built on fuzzy scope invites a parade of change orders that all look legitimate. Tight scope is your best defense.
• Unclear contingency rules. If the contract does not say who controls each contingency layer and what triggers a draw, expect friction later.
• Unreimbursed overruns you assumed you were covered for. Read closely which costs are reimbursable and which the contractor absorbs.

It helps to see where a GMP sits among the alternatives. A lump-sum contract shifts missed-scope and underestimation risk onto the contractor from day one, which is clean but gives you no visibility into cost. A cost-plus contract is fully transparent but risks weak cost control and an unhappy owner if nobody is holding the line. A GMP is the middle ground: it blends the cost-reimbursement mechanics of cost-plus with the price certainty of a lump sum.

One more thing worth knowing. If your lender is requiring a guaranteed maximum price, that does not automatically mean you need a GMP or cost-plus contract. The same price guarantee can be delivered inside a lump-sum contract, and open-book pricing can still be used during preconstruction under either format, sometimes at lower cost to you. A GMP ceiling can also be layered onto a cost-plus or time-and-materials contract when early scope is still evolving, giving you flexibility up front with a hard cap on top. The contract type should follow the project, not the other way around.

An honest read on your contract

If you have a GMP proposal in front of you, or a lender pushing you toward one, we are glad to read it with you and tell you plainly whether the scope, contingency, and savings language actually protect you. Send the plans or the bid set to our estimating team and we will give you an honest read, whether the job ends up ours or not.