Fixed-scope vs milestone contracts: pick the shape that matches what you know

OutsourcingVN is operated by Netbase JSC, a software supplier that signs these contracts, so treat this comparison as written by one side of the table. Most Netbase projects are fixed-scope contracts agreed after discovery; milestone-based arrangements are also available. The guide explains when each shape protects the buyer and when it quietly moves risk back onto them.

Contents

• What does each contract shape actually commit to?
• How do you decide which shape fits your project?
• How does a milestone contract work in practice?
• Worked scenario: a clinic-booking product at the contract table
• Which clauses matter whatever shape you choose?
• What questions should you ask a supplier about the contract?
• What goes wrong with each contract shape?
• How this guide is sourced and where it stops
• Common questions
• Bring your scope and your unknowns

What does each contract shape actually commit to?

A contract shape is a decision about who carries the uncertainty. The scope has to be fixed somewhere, and the only question is when and by whom.

Two points matter more than the table. A fixed-scope contract signed before discovery is a guess with a signature on it. And outcome-based contracts sound safest for the buyer but are the hardest to write, because a sales figure depends on marketing, stock and seasonality as much as on the software.

How does a milestone contract work in practice?

Netbase's delivery lifecycle runs from discovery and strategic alignment, through team assembly and architecture planning and agile execution with outcome-based milestones, to modular components, training and rollout, and ongoing support. In a milestone contract, each of those execution milestones becomes its own small fixed-scope agreement: a list of deliverables, an acceptance test, a date and a sign-off. The difference from one large fixed-scope contract is that milestone three is written after milestone two is accepted, with what milestone two taught both parties.

Netbase delivery runs with weekly reviews and a named project manager, which is what keeps a milestone contract honest between sign-offs. A weekly review is where a buyer learns early that a milestone is drifting, rather than finding out on the acceptance date.

A delivered example shows the shape. For a founder who is not named, Netbase delivered a bilingual English and Nepali classifieds platform: requirements, design, Laravel backend with REST APIs, OTP accounts, paid ads, search, ratings, messaging, event ticket ads, blog and forum, payments, multi-language SEO and AWS deployment. The classifieds platform record states it was delivered in six milestones over four months with training and six months of support. A platform with that many modules suits milestones because each group of features can be accepted, used and corrected before the next group is built on top of it.

Worked scenario: a clinic-booking product at the contract table

A founder plans a booking product for independent physiotherapy clinics: patient sign-up, clinic calendars, reminders, online payment and an admin view for clinic owners. The founder asks two suppliers for proposals. The scenario is illustrative and describes no client.

• Supplier A offers one fixed-scope contract for the whole product, signed before any discovery, with a long feature list copied from the founder's email.
• Supplier B proposes a two-week discovery, then a fixed-scope first milestone covering sign-up, calendars and reminders, with payments and the admin view outlined as milestones two and three.

The founder chooses B. Discovery shows that two pilot clinics need a deposit rule the founder had not mentioned, and that the chosen payment provider does not support it in one market. Under Supplier A's contract that discovery would have arrived mid-build as a dispute over whether the deposit rule was "in scope". Under B, it simply shapes milestone two, which is written and agreed after milestone one is accepted by the two pilot clinics.

The lesson is not that milestones always win. Had the founder already run a pilot on a no-code tool and written tested rules for every screen, a single fixed-scope contract would have been faster to agree and easier to hold the supplier to.

Which clauses matter whatever shape you choose?

At Netbase, for custom development the client owns the IP created for it; Netbase reusable modules and products are licensed, not transferred, and final terms are set in each project agreement. The IP ownership guide covers the wording to check, and the handover and exit guide lists what an exit clause should name.

What questions should you ask a supplier about the contract?

• What will discovery produce, and can I keep it if I do not continue? A discovery document you own lets you take the scope to another supplier.
• How are change requests estimated and approved? Ask to see a real change request template, not a promise of flexibility.
• Who signs acceptance on your side, and how long do I have to test? A short test window with no named tester is a warning sign.
• What happens to a milestone that fails acceptance? Look for a fix-and-retest loop before the next milestone starts.
• How do you report between milestones? Weekly written notes beat a monthly demonstration.
• Which parts of the build reuse your own modules, and on what licence? This decides what you own at the end.

What goes wrong with each contract shape?

• Fixed scope signed too early. Signal: the scope is a copy of your first email. Result: every clarification becomes a change request.
• Milestones with no end. Signal: milestone five is still "phase two tasks". Result: a time-and-materials engagement wearing a milestone label. Fix: agree a target number of milestones and a completion definition up front.
• Outcome contracts on outcomes nobody controls. Signal: the metric depends on your marketing spend or stock. Result: disputes about attribution instead of software.
• Acceptance by silence. Signal: "deemed accepted after five days". Result: defects found in week two are argued about as changes.
• Contract shape chosen to win the deal. Signal: fixed scope offered before a single question is asked. Result: hidden contingency, or corners cut later.

How this guide is sourced and where it stops

Statements about Netbase come from approved entries in the OutsourcingVN claim register, published in their registered wording and listed under Sources: the contract shapes Netbase agrees, its delivery lifecycle, weekly reviews, IP terms and the classifieds platform delivered in milestones. The methodology explains how those claims are reviewed. Netbase's published record shows milestone delivery on the classifieds platform; it holds no published outcome-based contract, so that column describes the shape in general rather than Netbase experience. Nothing here is legal advice, and no commercial figure, rate or payment term is published on this site.

Bring your scope and your unknowns

Project delivery sets out how Netbase runs discovery, milestones, change control and acceptance, and Custom Product Engineering is the service that delivers the build. Engagement models compares the wider ways to work with a supplier.

OutsourcingVN is Netbase's own outsourcing-services platform. Submit a project with what you know, what you are guessing and your target date, and a person will reply with the contract shape that fits and what discovery would need to settle first.

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