The verdict in three sentences
A vague requirements spec explains most of the 1-to-3 gaps between bids received for a B2B customer portal: each vendor prices its own interpretation of the need. Investing 10 to 20 internal days or EUR 4,000 to 12,000 of external advisory support in a precise document narrows the bid gap, speeds up the decision and protects against change orders. Consult 3 to 5 vendors, no more, with a scoring grid published from the start. The figures below come from the Lyon market and transpose closely to London once converted to GBP.
The standard structure of a customer portal spec
An effective spec runs 20 to 40 pages. It describes the business need and constraints, not the detailed technical solution: proposing the architecture is the vendor's job.
| Chapter | Expected content | Indicative pages | Common mistake |
|---|---|---|---|
| Context and objectives | Business, number of clients, quantified goals (e.g. 60% of orders online) | 2 to 3 | Non-measurable goals |
| Users and roles | Buyer, client accountant, sales rep, order desk, after-sales technician | 2 to 4 | Forgetting multi-site permissions |
| Functional journeys | Ordering, delivery tracking, invoices, after-sales claim | 8 to 15 | Listing screens without business rules |
| Integrations | ERP, CRM, after-sales tool, e-signature, payment | 3 to 6 | Not providing existing API documentation |
| Non-functional requirements | Performance, availability, GDPR, accessibility, security | 2 to 4 | Unrealistic demands (100% uptime) |
| Data and migration | Volumes, history to migrate, file quality | 1 to 3 | Underestimating data cleansing |
| Tender terms | Schedule, response format, scoring criteria, indicative budget | 2 to 3 | Hiding the budget, which skews bids |
The most valuable chapter is the one with functional journeys described with their rules: "a key account sees its negotiated prices and outstanding balance, a standard client pays by card above EUR 5,000". These rules make the difference between a EUR 45,000 bid and a EUR 110,000 bid.
Doing it alone or getting help: 2026 costs and timelines
Three options are available to a mid-sized industrial company. Amounts are 2026 estimates.
| Option | Cost | Writing time | Quality of bids received | Suits you if |
|---|---|---|---|---|
| 100% in-house | 10 to 20 days of manager time (EUR 6,000 to 14,000 internal cost) | 6 to 10 calendar weeks | Variable, 1-to-3 gaps common | Team has already run a web project |
| In-house with adviser review | EUR 4,000 to 6,000 | 4 to 6 weeks | Good | Clear need but little tender experience |
| Full advisory (workshops, writing, bid analysis) | EUR 8,000 to 12,000 | 4 to 8 weeks | Very good, 1-to-1.5 gaps | Project above EUR 70,000 or complex ERP integration |
| Paid scoping workshop with one vendor | EUR 2,000 to 6,000 | 2 to 3 weeks | Single bid, no competition | Existing trusted relationship |
For a portal estimated at EUR 60,000, an EUR 8,000 adviser represents 13% of the budget. It pays off if it avoids a EUR 15,000 change order, a frequent scenario when the ERP integration was poorly described.
Scoring criteria that pick the right vendor
Publish the grid in the tender pack. It forces bidders to answer point by point and makes comparison easier.
| Criterion | Suggested weight | What to ask for |
|---|---|---|
| Understanding of the need and response quality | 25% | Restated journeys, relevant questions |
| Comparable references | 20% | 2 B2B portals in production, reachable contacts |
| Price and pricing transparency | 20% | Breakdown by work package, day rate, assumptions |
| Method and schedule | 15% | Sprints, demos, acceptance testing, go-live |
| Maintenance and reversibility | 10% | Maintenance contract, code ownership, documentation |
| Proposed team | 10% | Named profiles, long-term stability |
Never give more than 30% to price: the cheapest bid is often the one that least understood the integration with your ERP.
Mini case study
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Nathalie, CIO of a lifting equipment manufacturer near Lyon (420 business customers, Sage X3 ERP), must launch a customer portal with orders, invoices and after-sales claims.
First attempt without a structured spec: four bids between EUR 38,000 and 115,000, impossible to compare. Second tender with an adviser at EUR 9,000 and 12 internal days: four bids between EUR 62,000 and 84,000, all based on the same ERP flows.
Calculation: the selected EUR 71,000 bid includes the Sage API from the start. The lowest initial bid relied on manual exports, which the adviser estimated at a EUR 20,000 change order once the real need surfaced. The EUR 9,000 support therefore avoided a likely net overrun of EUR 11,000, not counting three months of delay.
FAQ
Should the spec include a budget?
Yes, a range is enough, for example EUR 50,000 to 80,000. Without a budget, vendors imagine very different scopes and gaps often exceed a factor of 2.
How long should vendors have to respond?
Three to four weeks, with a Q&A session halfway. Under two weeks, the best vendors decline or answer with cautious, more expensive assumptions.
Should we write detailed technical specifications?
No. Describe business rules, volumes and integrations. Detailed specifications are produced during the first 2 to 4 weeks of the project, with the selected vendor.
How do we avoid change orders mid-project?
Require pricing by work package with explicit assumptions and keep a 10 to 15% budget reserve for adjustments. A spec that is precise about integrations sharply reduces this risk.
Should the spec address code ownership?
Yes. Require assignment of rights on the custom code, access to the Git repository and deployment documentation, so you can switch vendors without starting from scratch.
Let's scope your project. Send us your requirements spec or first notes: we will return pricing by work package, explicit assumptions and a schedule for your customer portal. 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.
