The verdict in three sentences
For a custom business app of around 60,000 GBP, a fixed price contract protects your budget only if scope is more than 80 % stable, because the agency already builds in a 15 to 30 % risk premium and bills every change as a change request. Time and materials looks cheaper, with day rates of 600 to 1,000 GBP in London or 1,200 to 2,000 USD in New York, but it shifts all overrun risk to you. The healthiest model for a CFO in 2026 is usually hybrid: a short fixed price discovery, then fixed price two week sprints under a contractual cap.
Fixed price, T&M, hybrid: what you actually pay
A finance director often receives two proposals for the same app: a fixed price of 60,000 GBP and a T&M estimate of 85 days. The figures do not compare directly. The fixed price includes insurance against the unknown; T&M shows production cost with no guarantee on days.
| Criterion | Fixed price | Time and materials | Hybrid: fixed discovery then fixed price sprints |
|---|---|---|---|
| Headline price in this example | 60,000 GBP | 85 days × 650 GBP = 55,250 GBP | 6,000 GBP discovery + sprints at 9,000 GBP |
| Risk premium included | 15 to 30 % | None | Small, per sprint |
| Who carries overruns | Agency first, then you via change requests | You, entirely | Shared, capped per sprint |
| Scope flexibility | Low | Full | High between sprints |
| Budget visibility | Good if scope is stable | Low | Good, sprint by sprint |
| Client side management effort | Acceptance at milestones | High, weekly day tracking | Medium, review every 2 weeks |
| Best fit | Frozen scope, detailed specification | Strong in-house product team | Business app that will evolve |
A useful benchmark: in 2026, most business app projects see scope move by 20 to 35 % between signature and go live. Beyond 20 %, fixed price turns into a string of change requests negotiated under deadline pressure, often at a higher rate than the original quote.
2026 day rates and the cost of the same app
The day rate alone tells you little: a team at 400 per day delivering in 120 days costs more than a team at 700 delivering in 65. Always compare total estimated cost and team composition.
| Provider | Day rate, order of magnitude 2026 | Estimated days, same scope | Estimated cost | Watch points |
|---|---|---|---|---|
| London agency | 600 to 1,000 GBP | 75 to 85 | 45,000 to 85,000 GBP | Actual seniority of the assigned team |
| New York agency | 1,200 to 2,000 USD | 75 to 85 | 90,000 to 170,000 USD | Blended rates hiding junior staff |
| UK senior contractor | 500 to 800 GBP | 85 to 100 | 42,500 to 80,000 GBP | Single person dependency, IR35 status |
| Eastern Europe (Poland, Romania) | 350 to 550 EUR | 90 to 105 | 31,500 to 57,750 EUR | Time zone overlap, QA discipline |
| African nearshore (francophone and anglophone) | 250 to 450 EUR | 90 to 110 | 22,500 to 49,500 EUR | Management cadence, acceptance testing |
For reference, Kolonell prices custom apps by tier: simple, 2,500,000 to 4,000,000 FCFA (3,810 to 6,100 EUR), medium, 4,000,000 to 7,000,000 FCFA (6,100 to 10,670 EUR), complex, 7,000,000 to 15,000,000+ FCFA (10,670 to 22,870+ EUR), with maintenance at 35,000, 75,000 or 120,000 FCFA per month (53, 114 or 183 EUR).
Clauses to demand whatever the model
Five clauses protect a CFO far more than the choice between fixed price and T&M.
- Code ownership: IP assignment on each payment, access to the Git repository from day one.
- Definition of done: written acceptance criteria per feature, acceptance window of 10 working days maximum.
- Change request procedure: estimate within 5 days, at the contract day rate, never above.
- T&M cap: alert at 80 % of budget consumed, contractual stop at 100 % without written approval.
- Exit and handover: documentation, deployment scripts and at least 2 days of knowledge transfer.
Add a 3 month warranty on defects after go live at no charge. That is market standard in 2026 and removes most acceptance disputes.
Mini case study
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Sarah, CFO of a mid-sized manufacturer near Manchester, wants a production order tracking app. She compares a fixed price of 60,000 GBP with T&M at 650 GBP over 85 days, so 55,250 GBP.
Mid project, the plant asks for batch traceability: +25 % scope. Under fixed price, the change request is quoted at 15,000 GBP, total 75,000 GBP. Under T&M, 85 days become 106, so 68,900 GBP, with no guarantee: the real overrun could have been 40 %.
With the hybrid model, Sarah pays 6,000 GBP for discovery, then 7 sprints at 9,000 GBP, total 69,000 GBP, with traceability built in sprint 5 instead of a secondary feature that is deferred. Final cost is close to T&M, with visibility every two weeks and the right to stop after any sprint. The 6,000 GBP saved against fixed price almost covers a year of maintenance.
FAQ
Is fixed price always more expensive than T&M?
For equal, stable scope, yes, by 15 to 30 % on average, because it pays for the agency's risk. If your scope changes by more than 20 %, change requests often reverse the equation.
How do we stop T&M from drifting?
Set a contractual cap, an alert at 80 % of budget and weekly reporting of days per feature. A 30 minute weekly steering call is enough on a 60,000 GBP project.
Is nearshore reliable?
Yes, with a stable team and clear management. Rates of 250 to 550 EUR a day can save 30 to 50 % of the budget, provided you plan rigorous acceptance testing and code reviews.
What if the agency refuses to assign the code?
Do not sign. IP assignment on payment is standard; without it you depend on the vendor for every change, at its rate.
Which sprint length should we choose?
Two weeks is the 2026 standard: long enough to ship a testable feature, short enough to limit the loss if one sprint of about 9,000 GBP disappoints.
Let's scope your project. Describe your app, how mature the requirements are and your deadlines, and we will propose the right contract model and a sprint plan. 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.
