What a GMP Contract With an Open-Book Cost Ledger Looks Like in Practice

A Guaranteed Maximum Price (GMP) contract caps what you will pay for a construction project. Open-book accounting means you can see every dollar spent against that cap. Together, they form the basis of owner-GC trust on large healthcare projects — but only if the mechanics behind them are actually implemented. This post covers what the cost ledger document looks like in practice, how invoices are submitted and reviewed, what happens at monthly GMP reconciliation meetings, how contingency is drawn versus change-ordered, and what happens when actual costs come in under the GMP. Where relevant, we reference JK Prestige's 320,000 sqft hospital tower (22-month program, North Carolina, 2025) as a practical reference.

The GMP Cost Ledger: What It Contains

The GMP cost ledger (sometimes called the Schedule of Values in a GMP context, though they are not identical) is a live document that maps every dollar in the GMP to a cost category. It is updated monthly and shared with the owner at each reconciliation meeting.

Standard Line Items in a Hospital GMP Ledger

A well-structured GMP ledger for a hospital project has the following primary categories:

1. General Conditions: Superintendent salaries, project engineer, project management office expenses, temporary utilities, sanitary facilities, site fencing and ICRA barriers, safety officer if dedicated, document control systems. General conditions typically run 8-12% of total construction cost on a hospital project.

1. Labor — Self-Perform Trades: Hours and burden (wages + benefits + payroll taxes) for GC's own crews performing framing, concrete, drywall, finish carpentry, and roofing. These are open to owner review at the daily timesheet level.

1. Material: All materials procured directly by the GC (structural steel, lumber, gypsum board, concrete, roofing materials, hardware). Material invoices from suppliers are included in the monthly invoice package.

1. Subcontract: Each subcontracted scope has its own line — mechanical, electrical, plumbing, medical gas, fire suppression, elevators, landscaping. The subcontract amount is fixed; changes to subcontract scope trigger a formal GC-to-sub change order that becomes visible in the ledger.

1. Equipment: Crane rentals, concrete pumps, temporary generators, forklifts. Rental invoices attached to monthly package.

1. GC Fee: The GC's profit and overhead markup. On hospital projects, fee is typically negotiated as a percentage of construction cost (commonly 3-5% on large projects) and is fixed at contract execution. It does not increase if costs increase.

1. Contingency: A negotiated line item (typically 3-5% of construction cost) held within the GMP to absorb unforeseen conditions — concealed site conditions, design gaps discovered during construction, minor scope changes that do not rise to an owner-directed change. The contingency is the GC's to manage, but draws on it are disclosed in the open-book ledger.

1. Owner's Allowances: If the owner retains certain scope as allowances (FFE, owner-furnished equipment, technology systems), these are tracked separately. Allowances are not part of the GC's cost and do not affect GC fee calculations.

On the 320,000 sqft tower, the GMP ledger ran to approximately 200 line items across these categories, updated monthly and distributed to the owner's project manager and facilities director before each reconciliation meeting.

How Invoices Are Submitted and Reviewed

Monthly pay applications (invoices) are submitted by the GC to the owner or owner's representative, typically on the first business day of each month covering the prior month's costs. In a GMP open-book contract, the pay application includes:

• Summary page: Total billed to date, previous billings, current month's amount requested, retainage withheld
• Schedule of values continuation sheet: Line-by-line breakdown of percentage complete by cost category
• Labor cost backup: Certified payroll or timesheet summaries for self-perform labor
• Material invoices: Supplier invoices for materials procured in the billing period
• Subcontractor pay applications: Each sub submits their pay application to the GC; the GC's application to the owner includes the sub's backup document
• Equipment rental invoices: Copies of rental agreements and invoices for the period
• Lien waivers: Conditional lien waivers from the GC and all major subs for the current period; unconditional waivers for the prior period

The owner's representative (or owner's project manager) reviews the package before approving payment. The review typically takes 5-7 business days. Discrepancies — a line item that increased without explanation, a sub billed for work not yet complete — are flagged in writing before payment is released.

This process differs from a lump-sum contract, where the GC's internal cost allocation is invisible. In the GMP open-book model, every dollar spent is traceable back to a supplier invoice or a timesheet.

Monthly GMP Reconciliation Meetings

Once per month, the GC presents the updated cost ledger to the owner. The agenda covers four items:

1. Cost to date vs. GMP: How much has been spent, what percentage of the GMP is consumed, and what the projected cost at completion is based on current burn rates
2. Contingency status: How much contingency remains, what draws have been made since the last meeting, and what risks are pending that may draw on remaining contingency
3. Pending change orders: Owner-directed scope changes that have not yet been priced, estimates in progress, and the projected budget impact
4. Look-ahead: Known cost events in the next 60-90 days — major subcontract mobilizations, long-lead material deliveries, scheduled scope completions

These meetings are not presentations. They are working sessions where the owner asks questions and receives direct answers. A GC who does not have answers at the reconciliation meeting is a GC who is not managing the ledger actively.

JK's reconciliation meetings for the North Carolina tower ran 90 minutes. The cost ledger was distributed three days before the meeting. Questions came in writing beforehand so the answers were prepared — not improvised at the table.

Contingency: Draw vs. Owner Change Order

This is the most consequential distinction in a GMP contract.

Contingency draws are costs absorbed within the existing GMP — the GC uses contingency to cover the item without increasing the owner's maximum price. Appropriate uses:

• Minor design gaps discovered during construction (a missing structural connection detail, a plumbing route that conflicts with a structural element and requires a re-route)
• Concealed site conditions not detectable by normal subsurface investigation
• Small scope additions requested by the GC's superintendent to improve constructability (at GC discretion, not owner-directed)

Owner change orders increase the GMP and require the owner's written approval. Appropriate triggers:

• Owner-directed scope additions (additional square footage, upgraded finishes, added equipment)
• Design changes initiated by the architect or engineer that increase construction cost
• Site conditions that were disclosed as a risk in the GMP but excluded from contingency coverage (documented in the contract)

The distinction protects the owner from a GC who continually draws down contingency for items that should be change-ordered — and protects the GC from being required to absorb every cost event within the original GMP regardless of origin.

In a properly structured GMP contract, the contingency draw authority is defined: the GC can draw contingency for items up to a threshold (commonly $25,000-$50,000 per item) without owner pre-approval, but must disclose all draws at the monthly reconciliation meeting. Items above the threshold require a written change request before the draw is made.

On the North Carolina tower, the contingency was approximately $4.2M on a $92M GMP. Over the 22-month program, approximately $2.8M was drawn in contingency — disclosed at every monthly meeting. The remaining $1.4M rolled into savings.

What Happens When Actual Costs Come in Under the GMP

If the project completes with actual costs below the GMP, the difference is GMP savings. What happens to those savings depends on the contract language negotiated at execution.

Three common structures:

1. Savings go entirely to the owner: The GC earns its negotiated fee and no more. All underspend returns to the owner. This structure gives the owner maximum protection but reduces GC incentive to pursue cost efficiencies aggressively.

1. Savings split between GC and owner: A negotiated percentage (commonly 50/50) of savings below the GMP is shared. The GC has incentive to find efficiencies; the owner shares in the benefit. This is the most common structure on hospital projects where the owner and GC have a collaborative relationship.

1. Savings go entirely to the GC: Rare on public or large institutional projects. More common on smaller design-build relationships where the GC took significant design risk.

JK operates on a split-savings model — typically 50/50 — because it aligns GC incentive with owner interest. A GC who earns nothing from finding cost efficiencies has no reason to look for them.

See how the GMP contract structure integrates with JK's broader delivery process, and review JK's healthcare project record — including the 320,000 sqft tower — at the hospital construction page.

What to Verify Before Signing a GMP Contract

Before signing, confirm these four elements are explicit in the contract language:

1. Contingency draw authority thresholds — what can the GC draw without your pre-approval?
2. Savings sharing formula — what happens to underspend at closeout?
3. Open-book access rights — are you entitled to request source documents (invoices, timesheets) at any time, or only at monthly meetings?
4. GC fee calculation basis — is GC fee calculated on total cost including contingency, or on base construction cost only? (The latter is owner-favorable; the former incentivizes the GC to draw contingency.)

Contact JK Prestige Constructor to review a sample GMP structure from a completed hospital project.

Get a free written estimate in 48 hours. call (904) 944-0278. A principal answers.