GMP tracking in Excel, and when a spreadsheet is enough
Most owners start in a spreadsheet, and some should stay there. The same eight rows, an honest column for the spreadsheet, and the cases where it is the right answer.
The things an owner on a GMP contract needs to see, one per row.
Quoted from its own pages on 9 September 2026, or marked not published.
From the product's own code, file and line in the source record.
No logos, no statistics, no ranking. Two descriptions side by side.
A spreadsheet holds numbers. A ledger holds what happened to them.
A spreadsheet is the most honest tool there is: it does exactly what the person who built it typed, and nothing more. On a GMP contract that is also its limit. The sheet holds the contingency balance; it does not hold who moved it, why, on which day, or which version of the baseline it was true for. The person who built it carries all of that in their head, and it leaves with them.
The owner side of a guaranteed maximum price contract.
Costwitness starts at the GMP amendment, keeps contractor and owner contingency as two separate funds, records the cause of every change order and the date its notice clock started, follows buyout package by package against the GMP lines, and works out the shared savings on the cap and carve-outs written in the amendment. It does not do accounting, invoices or development budgets. One project, read from the owner's side, in nine modules.
Eight things an owner needs, and what a spreadsheet does with each.
| What the owner needs | Costwitness | A spreadsheet |
|---|---|---|
| Anchored to the GMP amendment | Yes. The baseline is built from the GMP amendment and the schedule of values. | Only if somebody keys it in and keeps a copy of every version. |
| Two separate funds, owner and contractor | Yes. Contractor and owner contingency on separate ledgers, each draw dated and documented. | Two columns, if the person who set it up knew to make two. |
| Change orders classified by cause | Yes. Cause decides which fund pays: owner scope, design gap, unforeseen, coordination, unclassified. | A column, with no record of who changed it or when. |
| Notice date recorded from the event date | Yes. The notice clock runs from the day the condition was recognized, not the day it was typed in. | A date somebody remembers to type; nobody counts the days for you. |
| Buyout tracked against GMP lines | Yes. Per package: GMP line value, awarded value, variance, award date. | A second sheet, reconciled by hand. |
| Shared savings with cap and carve-out logic | Yes. Cap as fixed, percent of GMP or percent of fee; carve-outs excluded from the pool. | A formula that is right until somebody edits the cell. |
| Pricing basis | Per active project, unlimited users. Free 14-day trial, no card. | The time of whoever maintains it. |
| Built for | The owner side of a GMP contract. | Whoever owns the file. |
Costwitness column from the product's own code; see Per active project. Never per seat. for the pricing basis.
- One project, and one person who runs it from the first pay application to the last and is not going anywhere.
- A contract with no shared savings clause and no notice periods to count.
- Nobody outside the team, no lender and no board, will ask to read the record.
If all three hold, keep the spreadsheet. Costwitness would be a second place to type the same numbers.
- A lender or a board asks to read the record, and the sheet has no history to show them.
- A change order is reclassified and nobody can say who did it, when, or what it cost.
- A notice period is missed because the deadline was a date somebody had to remember.
If one of these has already happened, the spreadsheet has told you what it cannot hold.
- No invoice or accounts payable automation. Costwitness records what a pay application claims; it does not approve or pay invoices.
- No development budget module. Land, soft costs and financing are not in it; the GMP contract is.
- No design document workflow. Drawings, submittals and RFIs to the designer live elsewhere.
Asked before choosing.
Can I keep tracking a GMP contract in Excel?
Yes, and many owners do. The question is who else will need to read the record, and whether the person who built the sheet will be there when they ask. The section above says when the spreadsheet is the right answer.
What does a spreadsheet lose that Costwitness keeps?
Who changed a cell and when. A spreadsheet holds the number; it does not hold the reason a change order was reclassified, the day a notice clock started, or the version of the baseline the number was true for.
Can I bring my spreadsheet into Costwitness?
The schedule of values can be imported as a sheet; that is how the baseline is built. Ledgers of draws and change orders are entered against it, with a date and a cause on each.
How is Costwitness priced against a spreadsheet?
A spreadsheet costs the time of whoever maintains it. Costwitness is priced per active project with unlimited users, with a free 14-day trial and no card asked for.
Start a free 14-day trial
Create the account, build the baseline from your GMP amendment and the schedule of values, and read the first month from the owner's side.