Change work is not the same work at a smaller size
An hour of framing inside the planned sequence and an hour of framing after the drywall is up are different hours. The second one involves a trip back, tools re-staged, protection reset, possibly something already finished taken apart, and a crew pulled off whatever they moved to. That inefficiency is the single most under-priced element of change orders in small contracting, because it does not appear on any invoice and it is invisible to a customer looking at a materials list.
The remobilization line in this calculator is where it goes. It is not padding and it is not a penalty. It is the hours you will actually spend that are not the added work itself. On a small change it commonly exceeds the productive hours, which is why very small changes are sometimes priced at a flat minimum rather than by the hour.
Carrying overhead and margin on changes, not just cost
Overhead is recovered per hour of billable field time. A change adds field hours, so it adds overhead, and pricing the change at cost plus a small percentage recovers less overhead per hour than the base contract does. Do that enough times and the job finishes at a lower blended margin than the one you bid, while the total dollars went up. That is the particular sting of change orders: the volume grows and the profitability falls.
Some contractors set a higher target margin on changes than on the base contract, and the justification is not opportunism. Change work is less efficient, carries more coordination, and often disrupts the sequence for work that is already priced. Whether the market accepts that is a separate question, and on repeat commercial work the change order markup is frequently fixed in the contract. Either way, put a number on it before the first change rather than negotiating it under pressure with a crew standing around. The job cost and markup calculator sets the base contract number the same way.
The three things a change order should settle
| Element | What goes wrong when it is left out |
|---|---|
| Scope of the added work | Disagreement later about what the price included |
| Price and how it was derived | Argument about the rate rather than about the work |
| Days added to the completion date | Original deadline stays binding while the job grows |
The third one is the one people skip. A change approved on price alone does not move the schedule, so a job that absorbed six changes can be contractually late while being exactly on the timeline everyone verbally agreed to. State the days in the document. Whether a schedule extension needs to be claimed in a particular form or within a particular window depends on the contract and, for some work, on state law. That is a conversation for an attorney who handles construction contracts where you work.
Getting authorization before you build it
The practical failure is not pricing. It is doing the work on a verbal go-ahead because the crew is on site and stopping seems absurd, then invoicing for it and discovering the person who said yes was not the person who could say yes, or that the contract requires changes in writing. Whether an oral approval, an email, or a text creates an obligation varies with the contract terms and with the law of the state, and it varies enough that the only responsible answer here is that a construction attorney should tell you what your paperwork needs to look like. What is universal is that written and signed before the work is far easier to collect than anything reconstructed afterwards.
There is also a middle path worth having ready. When a change is discovered mid-task and stopping would cost more than the change, a short written authorization to proceed on a not-to-exceed basis, signed on site, is better than nothing and better than a full stop. Have the form on your phone before you need it. What that form should say is something a lawyer drafts once for your business.
When absorbing a change is the right call
Sometimes it is. A trivial addition on a job you want a reference from, a change that came from an ambiguity in your own scope document, or a genuine error on your part are all reasonable to eat, and nickel-and-diming a good customer over an hour of work is a poor trade. What makes that decision sound rather than sentimental is knowing what you are giving up, which is the last section of the output above. Absorb a change knowing it cost you a specific number of dollars, and the ones you should not absorb become obvious. Absorb them without pricing them and the total only shows up at the end of the job.
Questions people ask
Should change orders carry a higher markup than the base contract?
It is common practice and there is a defensible reason for it: change work is less efficient, it disrupts sequencing that was already priced, and it consumes coordination time out of proportion to its dollar value. What percentage the market will bear varies by trade and by customer type, and on many commercial contracts the change order markup is fixed in advance by the agreement. The important thing is that the rate is agreed before the first change rather than negotiated during one, because a rate proposed mid-dispute reads as opportunism whatever the arithmetic behind it.
How do I price a change that reduces scope?
A deductive change should return the direct cost of the removed work, but not necessarily the full overhead and margin, because your overhead did not shrink when a task came off the list and the mobilization for the job did not get cheaper. How much comes back is a negotiation and it should be governed by the contract. Run this calculator on the removed work to see the cost and price separately, then decide what portion of the margin is genuinely released. Returning the full priced amount on a deduction while absorbing the inefficiency of the disruption is how a scope reduction can lose money.
What if the customer refuses to sign but wants the work done?
That is a business decision with legal consequences, and the consequences depend on your contract and on the law where the work is. Practically, the exposure is that you finance the work and then have to prove entitlement to be paid for it, which is a much weaker position than holding a signature. Options people use include a written not-to-exceed authorization, an email confirming the instruction and the price with a request to reply, or declining to proceed. Which of these actually protects you is a question for a construction attorney licensed in your state, and it is worth asking once rather than discovering the answer during a dispute.
Do small changes need paperwork too?
The small ones are exactly where the money leaks, because each is individually not worth the friction and collectively they add up to a meaningful share of the margin. A practical approach many contractors use is a minimum charge that reflects the remobilization reality, and a simple one-page form rather than a formal document for anything under it. The paperwork burden is real, so make it light rather than making it optional.
Does a change order affect retainage and the payment schedule?
Usually yes, and the mechanism should already be in the contract. Added contract value normally flows through the same progress billing and holdback arrangement as the base work, which means the change also has retainage held against it and is paid on the same lag. That is worth modelling before you commit to a large change on a job that is already stretching your cash, and the retainage and cash flow calculator shows the shape of it.