The verdict in three sentences
Fixed price buys predictability, but the vendor embeds a risk margin of 15 to 30% that you pay even when everything goes well. Time and materials (T&M) bills the time actually spent, with an average overrun of 20 to 40% when scope is not held. For a 4 to 6 month application, the healthiest model in 2026 is phased fixed price preceded by a short T&M discovery phase.
Reading the two quotes side by side
A wholesale SME receives two proposals for its B2B ordering portal: a EUR 48,000 fixed price (about GBP 41,000), and a T&M offer at EUR 650 per day estimated at 62 days, or EUR 40,300. T&M looks EUR 7,700 cheaper. It only is if the estimate holds. London agencies typically charge 20 to 30% more than the figures below; the logic is identical.
| Criterion | Fixed price EUR 48,000 | T&M EUR 650/day |
|---|---|---|
| Quoted price | EUR 48,000 firm | EUR 40,300 estimated (62 days) |
| Embedded risk margin | 15 to 30%, i.e. EUR 6,300 to 11,000 | None, the risk is yours |
| Scope change | Priced change request, often EUR 700 to 800/day | Absorbed as you go |
| Progress visibility | Contractual milestones | Weekly timesheet |
| Quality when budget is tight | Temptation to deliver the minimum | Temptation to stretch time |
| Announced timeline | 5 months | 4 to 6 months |
| Late-delivery penalties | Negotiable, 0.5 to 1% per week | Rarely included |
Three costed scenarios
The real comparison is on probable final cost, not on the headline price.
| Scenario | Final fixed-price cost | Final T&M cost | Winner |
|---|---|---|---|
| Stable scope, no surprises | EUR 48,000 | EUR 40,300 | T&M (-16%) |
| Moderate overrun (+20% effort) | EUR 48,000 + EUR 4,000 change = EUR 52,000 | EUR 48,400 | T&M (-7%) |
| Heavy overrun (+40% effort) | EUR 48,000 + EUR 9,000 changes = EUR 57,000 | EUR 56,400 | Tie |
| Misunderstood need (+60%) | EUR 48,000 + EUR 15,000 = EUR 63,000 | EUR 64,500 | Fixed price |
| Module dropped mid-project | EUR 48,000 (unless reduction clause) | Saving of EUR 8,000 to 12,000 | T&M |
| Vendor 6 weeks late | Possible penalties, EUR 1,400 to 2,900 | Nothing recoverable | Fixed price |
T&M wins when the need is clear and the internal team is available to make decisions every week. Fixed price protects you when the need is fuzzy or the sponsor has no time to steer.
The clauses that make the difference
Whichever model you choose, five clauses prevent most disputes:
| Clause | Fixed price | T&M | 2026 recommendation |
|---|---|---|---|
| Change procedure | Mandatory | Useful | Pricing within 5 working days, written approval |
| Spending cap | Not applicable | Essential | Alert at 80%, stop at 110% |
| Acceptance and warranty | 30 to 90 days warranty | Often missing | Require 60 days in both cases |
| Code ownership | To be specified | To be specified | Full assignment on final payment |
| Reversibility | Documentation and Git repository | Same | Repository access from day one |
The recommended hybrid model
Phase 1 discovery on T&M, 8 to 12 days, about EUR 5,000 to 8,000: workshops, user stories, mock-ups, architecture. Then fixed-price phases of 6 to 8 weeks, each priced from the discovery output. You keep fixed-price predictability without paying a maximum risk margin, since uncertainty was removed upfront. The vendor can lower its margin to 10 to 15%.
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Mini case study
Sophie, CFO of a 45-employee wine trading SME, applies the hybrid model. T&M discovery: 10 days at EUR 650, or EUR 6,500. Discovery shows that a carrier dispute module, included in the original fixed price, can wait for version 2. Phase 1 fixed price: EUR 24,000, phase 2: EUR 15,000. Total: EUR 45,500 for a better-targeted scope, versus EUR 48,000 under the original fixed price or a EUR 56,000 risk on pure T&M. The portal ships in 4.5 months and absorbs 70% of phone orders, saving about 25 hours of data entry per week.
FAQ
Is T&M always cheaper?
On the headline price, yes, usually by 10 to 20%. On final cost, only if the overrun stays below 15 to 20%, which requires an internal owner available at least half a day a week.
What day rate is normal in 2026?
In continental Europe, EUR 550 to 750 per day for a senior agency developer, EUR 800 to 1,000 for an architect or senior project manager. In London, expect GBP 600 to 900 for the same profiles.
Can you negotiate the risk margin of a fixed price?
Yes, by reducing uncertainty: precise requirements and approved mock-ups often secure an 8 to 12% reduction on the fixed price.
How do you control a T&M engagement?
Require a weekly timesheet per task, a contractual cap and a demo every 2 weeks. Beyond a 10% variance on a sprint, a scope review is needed.
What does phased fixed price change in practice?
Each 6 to 8 week phase is paid on acceptance. You can stop or redirect after each phase without risking more than EUR 15,000 to 25,000 committed.
Let's scope your project. Send us your two quotes or your need: we propose a short T&M discovery then phased fixed price, with an indicative budget and a firm schedule. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.
