GMP Contracts in Hospital Construction: What Open-Book Cost Ledgers Actually Reveal

A Guaranteed Maximum Price (GMP) contract is the standard delivery structure for complex hospital construction for a reason: it gives the owner a price ceiling, a line-item view of actual costs, and a contractual mechanism for sharing savings when the project comes in under budget. But the GMP is only as honest as the cost ledger behind it. An open-book GMP and a GMP with a black-box accounting structure are not the same instrument, and the difference matters enormously when you are managing a $40M hospital tower budget.

This post explains how GMP contracts work, what open-book cost accounting actually looks like in practice, how contingency is structured and split, and what happens when a project comes in under the GMP ceiling.

GMP vs. Lump Sum vs. Cost-Plus: The Structural Differences

Before going into GMP specifics, the three primary contract structures in hospital construction need to be distinguished:

Lump sum (also called a stipulated sum) is a fixed price for a fixed scope. The GC takes full risk on costs. If they build it for less, they keep the difference; if costs exceed the agreed price, they absorb the loss. For complex hospital projects with evolving design documents, lump sum creates a misalignment: the GC is incentivized to cut costs and submit change orders on scope ambiguities, while the owner is holding a fixed price that no longer reflects the true scope.

Cost-plus is the opposite: the owner pays all actual costs plus a fixed fee or percentage. The GC takes no cost risk at all. Cost-plus can work in early preconstruction phases when the scope is not defined, but on its own it provides no price ceiling and no owner protection against cost overruns.

GMP sits between the two. The owner pays actual costs up to a ceiling, plus a fixed fee. The GC takes risk on anything above the ceiling. Costs below the ceiling may be shared between owner and GC per the savings-sharing provision. The GC is incentivized to control costs without being incentivized to cut scope.

For hospital construction — where design changes happen during construction, long-lead MEP (Mechanical, Electrical, and Plumbing) equipment arrives on unpredictable timelines, and phasing decisions can shift costs between line items — GMP provides the right incentive structure. It also creates the right framework for open-book accounting, which is where the real value lies.

What Open-Book Means: Every Invoice Visible to the Owner

In an open-book GMP, the owner has direct access to the full cost ledger: every subcontractor invoice, every material purchase order, every equipment rental charge, and every GC-level general conditions cost. "Open book" is not a general philosophy — it is a contractual right with specific terms.

In practice, open-book cost accounting means:

• Subcontractor invoices are reviewed by the owner (or owner's representative) before payment is approved. The owner sees the line-item cost, not just a GC billing rollup.
• Material purchase orders are disclosed. If the framing contractor invoices $84,000 for structural steel and the owner wants to see the mill pricing, they can.
• General conditions costs are itemized. Superintendent salaries, trailer costs, temporary utilities, insurance, and site security are listed separately — not buried in a fee percentage.
• Owner's contingency and GC contingency are tracked separately, with draw approvals required before funds are released from either pool.

This is meaningfully different from a GC who says "our GMP is open book" but provides only monthly cost reports aggregated at the trade level. Real open-book accounting requires a shared cost management platform — or at minimum, an audit right that the owner exercises regularly, not just at closeout.

At JK Prestige, the open-book ledger is not a closeout document. It is a live record that the owner's representative can access at any point in the project. The process is documented in The JK Way, including the weekly budget variance reports that accompany every construction schedule update.

How Contingency Is Structured in a GMP Contract

GMP contingency is not a single pool. In a well-structured healthcare GMP, contingency is split into at least two distinct buckets with different ownership and different draw protocols:

Owner's Contingency

Owner's contingency sits outside the GMP ceiling. It is the owner's reserve for scope additions — changes in program, additions to the clinical design that emerge during construction, equipment changes initiated by the clinical team. Draws from owner's contingency require owner authorization and are processed as formal contract modifications.

Owner's contingency on a hospital project typically runs 5 to 10% of the GMP value, depending on the design completion level at the time the GMP is established. A GMP set at 50% design documents carries more uncertainty than one set at 90%.

GC Contingency

GC contingency sits inside the GMP and is owned by the GC to cover cost exposure within the current scope — subsurface conditions, trade scope gaps, minor design clarifications that do not constitute owner-directed changes. The GC can draw from this pool without a formal change order, but draws must be documented with a reason code and disclosed on the cost ledger.

In an open-book GMP, the owner can see every GC contingency draw. This is where open-book accounting reveals something a black-box GMP hides: whether the GC is using contingency to cover legitimate field conditions or to absorb cost overruns caused by their own bidding gaps.

A GC who consistently draws down GC contingency by month 6 of a 22-month program is either managing construction in an unusually difficult site environment — or they underbid the subcontractor packages and are covering the gap with contingency.

What Happens When Actual Costs Beat the GMP

Savings sharing is the contractual provision that governs what happens when the project closes out below the GMP ceiling. The specific split is negotiated at contract signing, but a common structure is 50/50 between owner and GC.

This is important for two reasons:

First, it gives the GC a financial incentive to control costs throughout the project rather than spending up to the ceiling. A GC on a cost-plus contract with no GMP ceiling has no particular reason to push for lower subcontractor pricing or to avoid over-ordering materials — those costs all flow through to the owner. On a GMP with savings sharing, every dollar saved below the ceiling is worth half a dollar to the GC.

Second, it gives the owner a concrete benefit when the GC's preconstruction work was accurate. A GC who competitively bids all subcontractor packages, manages GC contingency conservatively, and delivers under the GMP ceiling generates a financial return to the owner at closeout — not just a project that stayed on budget.

On JK Prestige's hospital projects, the GMP is established at or before 90% design documents, which gives the cost data enough specificity to support a tight contingency split. Savings sharing provisions are standard in our healthcare contracts. See the full GMP and preconstruction process on our hospital construction expertise page.

Where GMP Contracts Break Down — and How to Prevent It

A GMP contract does not automatically protect the owner. Three failure modes are common in hospital construction GMPs:

1. The GMP Is Set Too Early

If the GMP is established at 30% design documents, the price ceiling is based on assumptions, not scope. The GC builds a large contingency into the GMP to cover the unknown, and the owner ends up with a ceiling that provides little protection because everything is covered under contingency. The GMP feels safe but offers little discipline.

The fix: insist on a GMP not before 60% design documents, and preferably closer to 90%. Accept a higher preconstruction fee in exchange for a more defensible GMP.

2. The Owner Doesn't Exercise the Audit Right

Open-book is only valuable if the owner uses it. A healthcare developer who receives monthly cost reports but never reviews subcontractor invoices or GC contingency draws is not operating an open-book contract — they are on a cost-plus contract with a ceiling they hope holds.

The fix: assign an owner's representative (OPM) with authority to review invoices and contingency draws monthly, not at closeout. If you do not have internal staff for this, hire an independent owner's project manager.

3. Change Orders Are Used to Reconstruct the GMP

This is the most common failure mode in healthcare construction: the GC bids low to win, then reconstructs their margin through change orders on scope items that were ambiguous in the contract documents. The GMP ceiling holds, but actual owner costs exceed it through contract modifications.

The fix: require a detailed scope of work document at GMP signing that explicitly identifies inclusions, exclusions, and allowances. Any change order should require the owner to identify which scope document section was ambiguous. A GC who cannot point to an ambiguity should not get a change order approved.

Why JK Prestige Uses GMP for All Hospital Work

JK uses Guaranteed Maximum Price contracts on every hospital project because it aligns the GC's incentives with the owner's interests throughout the project lifecycle — not just at the bid date. The open-book cost ledger is not a negotiation tool; it is the operating baseline from which every budget conversation starts.

On our largest hospital project — a 320,000 sqft tower completed in North Carolina in 2025 on a 22-month program — the GMP was established at 85% design documents with a documented savings-sharing provision. The cost ledger was reviewed monthly with the owner's project manager. GC contingency was drawn with reason codes and reported in the weekly owner summary.

That is what open-book means in practice.