Time and Materials vs Fixed Price: Which Contract Wins?
The short answer: A fixed-price contract quotes one total for a fully defined scope — you carry the risk of the job running long, and you keep the reward when it runs short. Time and materials (T&M) bills the customer for the actual hours worked plus materials at a markup — the customer carries the overrun risk, but you have to prove every hour and every part. Use fixed price when the scope is clear and you have real cost history; use T&M when the work is genuinely open-ended. Either way, the model only protects you if you know your true cost — and CRMb builds that number from your crew's actual punched hours and your average-cost materials, so both contract types are priced on facts instead of hope.
Contract type is a risk decision, not a paperwork decision. It sets who eats the cost when a job goes sideways, how you get paid, and how much of your work is spent defending an invoice. Choose it deliberately, per job.
How fixed-price contracts work
A fixed-price contract — also called lump sum — commits you to one number for a defined scope, agreed before the work starts. Frame that porch, replace that unit, clean that building: one price, regardless of how many hours it actually takes.
The appeal to the customer is certainty. They know the total before they sign, and a single confident price reads as professional next to a competitor who can only offer "we'll see." Fixed price sells.
The appeal to you is upside. Once you own the risk of the job running long, you also own the reward when it runs short. The crew that finishes in six hours what you priced at eight earns the full price — so your speed, your tools, and your training all flow straight to margin instead of shrinking the bill.
The catch is the estimate underneath it. A fixed price is only as safe as the cost you built it on. Estimate the hours from memory, be wrong the same direction every time, and you lose money on every job at scale — with a smile. Fixed price rewards businesses that know their numbers and quietly punishes the ones that guess.
How time and materials contracts work
Time and materials bills the customer for what the job actually consumes: labor hours at an agreed rate, plus materials — usually at cost plus a markup to cover handling and overhead. There is no single total agreed up front; the invoice reflects the real work done.
T&M is the honest choice when nobody can define the scope yet. You cannot quote a fixed price to fix a leak you have not found, or to renovate behind a wall you have not opened. Billing for actual time protects you from eating the cost of an unknown that turns out to be bigger than anyone expected.
But T&M shifts the burden of proof onto you. Every hour has to be documented, every material accounted for, or the customer questions the bill. An open meter also makes people nervous — "we'll bill you for the time" is the sentence that loses cautious customers to a competitor quoting one number. And because you bill by the hour, getting faster shrinks the invoice, so T&M quietly pays you less for being good at your trade.
The safeguard that makes T&M work is documentation. When the hours on the invoice trace back to real punch-in and punch-out times on that job, and the materials trace to what actually left your inventory, the bill is unarguable. That traceability is the whole game.
Who carries the risk
The single clearest way to choose is to ask who should carry the overrun risk on this job.
| Fixed price | Time and materials | |
|---|---|---|
| Who owns overrun risk | You (the contractor) | The customer |
| Customer knows total up front | Yes | No |
| Rewards a fast crew | Yes — speed becomes margin | No — speed shrinks the bill |
| Burden of proof on the invoice | Low — price was agreed | High — every hour and part |
| Best when scope is | Clear and well-defined | Unknown or open-ended |
| Biggest danger to you | Underestimating the job | Undocumented hours in dispute |
Fixed price is a bet on your own estimate. T&M is a bet that you can document the work well enough that the customer trusts the bill. Neither is universally right — the right answer depends on how well you can predict the job and how well you can prove the hours.
When to use which
Match the contract to the certainty of the scope:
- Fixed price — standard installs, repeat jobs, cleaning and maintenance, anything you have done enough times to know the honest average hours. Clear scope plus real cost history is exactly where fixed price makes the most money.
- Time and materials — diagnostics, emergency repairs, renovations behind walls, any job where the extent is genuinely unknown until you are in it. T&M protects you from pricing something you cannot yet see.
- A not-to-exceed hybrid — bill T&M but cap the total. The customer gets the fairness of paying for actual time with the safety of a ceiling, and you get a bridge while you gather enough job history to quote a confident fixed price later.
Most established businesses run both: fixed price on the predictable work, T&M on the unknown, and a not-to-exceed cap on the jobs in between.
Protecting your margin on either model
Both contract types depend on the same foundation — knowing what an hour of your crew actually costs you. Not the wage, the fully loaded cost: wage plus payroll taxes, insurance, equipment, vehicle, and a share of overhead spread across billable hours. That labor burden is almost always 25% to 40% above the raw wage, and it is the number that decides whether your rate or your fixed price actually makes money.
The discipline is the same for both:
- Know your true cost per hour before you set any rate or any fixed price. Price a T&M rate below your loaded cost and you lose money on every hour; price a fixed job below cost and you lose it all at once.
- Price to a target margin, not a markup — divide cost by
(1 − margin)so the profit you wanted actually lands. - Check every finished job against what it really cost. This is where fixed-price estimates get sharper and where T&M invoices get defensible.
When your crew punches in and out on the job with Punch, those hours flow into CRMb as real labor cost, and your materials are costed at their average cost as they leave inventory. Reports then shows the margin on each job against its actual punched hours and material spend — so a fixed price gets validated against reality and a T&M invoice is built from documented time, not a guess. Your quotes and invoices can pull that real labor and those materials straight from the job, and the public share link lets the customer sign off without a printer.
Frequently Asked Questions
Is time and materials or fixed price better for a contractor?
Neither is universally better — it depends on the scope. Fixed price is better for well-defined, repeatable work because it rewards a fast crew and reads as professional to the customer. Time and materials is better for open-ended work like diagnostics and repairs where you genuinely cannot predict the hours. Most established contractors use fixed price on predictable jobs and T&M on the unknowns.
Who takes on the risk in a time and materials contract?
The customer carries the overrun risk in a T&M contract, because they pay for the actual hours and materials the job consumes rather than a capped total. In exchange, the burden of proof shifts to you — every hour and every material on the invoice has to be documented, or the customer will question the bill.
What is a not-to-exceed contract?
Not-to-exceed is a hybrid of the two: you bill time and materials but promise the total will not pass a set ceiling. The customer gets the fairness of paying for actual time with the safety of a capped number. It is a useful bridge while you collect enough job history to quote a confident fixed price.
How do I bill time and materials without disputes?
Document everything and make the hours traceable. When the labor on the invoice traces back to real punch-in and punch-out times on that specific job, and the materials trace to what actually left your inventory, the bill is unarguable. Vague "8 hours of labor" lines invite questions; hours backed by punched time do not.
How do I set a fixed price without losing money?
Estimate the honest average labor hours, multiply by your fully loaded cost per hour, add materials, then price to a target margin by dividing cost by (1 − margin). The safeguard is checking every finished fixed-price job against its real cost, so your estimates get sharper over time instead of repeating the same wrong guess.
Getting started with CRMb
Look at your last ten jobs and sort them by how well you could have predicted the scope going in. The predictable ones should have been fixed price; the genuinely unknown ones should have been T&M. That sort is your pricing policy.
CRMb captures your crew's punched hours and average-cost materials on every job, then shows the true margin in Reports — so your fixed prices get validated against reality and your T&M invoices are built from documented time. It runs on Mac, iPad, and the web, sharing one backend with Punch. Start your 14-day free trial and price both contract types on numbers, not hope.