Invoiced cost is the last number on a construction project to move, which makes it the worst one to watch if the goal is catching an overrun while there is still time to do something about it. By the time an invoice lands, the money is already committed, and usually already spent. The number that moves first is the one most cost tracking ignores: what has been ordered but not yet billed.
Three numbers, not one
A DIN 276 cost plan gives you a budget per cost group. That is one number. Committed cost, purchase orders and contracts issued against that cost group whether or not they have been invoiced yet, is a second. Actual cost, what has actually been billed and paid, is a third. Watching only budget against actual hides the middle number, and the middle number is where an overrun shows up first.
An overrun that shows up before a single extra invoice arrives
| KG 300, Bauwerk-Baukonstruktion | Amount (EUR) |
|---|---|
| Budget | 2,000,000 |
| Committed (POs and contracts issued) | 2,150,000 |
| Actual (invoiced to date) | 1,200,000 |
Invoiced cost is running comfortably under budget, 1.2 million against a 2 million plan. Anyone watching only that comparison would call this cost group healthy. It is already 150,000 EUR over budget on a committed basis, and every one of those committed euros will eventually become an invoice. The gap between committed and invoiced is not upside, it is a bill that has not arrived yet.
A Nachtrag needs its own approval, not a quiet edit
When a cost group is trending over, the honest move is a formal Nachtrag, a change order that gets evaluated and approved on its own terms, rather than editing the original budget cell and losing the record of what changed and why. A silent edit erases the question a lender, an investor, or your own future self will eventually ask: was this always the plan, or did it move.
Why versions beat one mutable number
REPM keeps cost plan versions with their own approvals, so a Nachtrag becomes a new version sitting alongside the original rather than overwriting it. The budget, the committed total and the actual cost all live on the same development record, which is the same record that later becomes the asset's lease and rent history once it is built. Nothing about the overrun has to be reconstructed from an email thread months after the fact.
Try it against a real cost plan. Start a free REPM Lite trial at app.repm.cloud and watch committed cost move ahead of invoiced.
FAQ
What is the difference between committed and actual cost?
Committed cost is the total of purchase orders and contracts issued against a cost group, whether or not they have been invoiced. Actual cost, sometimes called Ist-Kosten, is what has actually been billed and paid. Committed cost moves first.
Why track committed costs if the money hasn't been paid yet?
Because it will be. A signed purchase order is money the project has already promised to spend, and ignoring that until the invoice arrives means discovering an overrun months after there was still room to negotiate scope or renegotiate a contract.
What is a Nachtrag?
A formal change order or supplement to an existing contract or budget, evaluated and approved on its own terms rather than folded silently into the original number. It preserves the record of what changed, when, and why.
Does revising a cost plan lose the original budget figure?
Not if the system keeps versions. A Nachtrag creates a new cost plan version alongside the original, so the initial budget stays visible even after an approved revision changes the working number.