The verdict in three sentences
A custom billing portal costs 30,000 to 70,000 EUR in 2026, including accounting/ERP and PSP (Stripe/GoCardless) integration. Expect 12 to 18 weeks split into 4-5 sprints and 500 to 1,100 EUR/month maintenance. The real ROI is collections: automated reminders and online payment recover 15 to 30 days of DSO.
Sprint-by-sprint roadmap
The project advances through usable increments, each delivering measurable value. Here is a typical 16-week roadmap.
| Sprint | Weeks | Deliverable | Value |
|---|---|---|---|
| Scoping & UX | 1-2 | Journeys, data model | Scope locked |
| Auth & invoices | 3-6 | Secure space, viewing | No more manual sends |
| Online payment | 7-10 | Stripe/GoCardless, receipts | Instant collection |
| Auto reminders | 11-13 | Day+7/15/30 scenarios | Falling DSO |
| ERP integration | 14-15 | Invoice/payment sync | Books up to date |
| QA & go-live | 16 | Testing, training | Launch |
Collections ROI: DSO before/after
DSO (average days to pay) is the crux. Here is a 2026 order of magnitude for a mid-cap billing 6M EUR/year, about 16,400 EUR collected per day.
| Metric | Before portal | After portal |
|---|---|---|
| Average DSO | 58 days | 34 days |
| Days recovered | - | 24 days |
| Cash freed | - | ~394,000 EUR |
| Reminder time/month | 22 h | 4 h |
| Online payment rate | 0% | 61% |
| Invoice disputes/month | 14 | 5 |
At a 5%/year cost of cash, 394,000 EUR freed represents about 19,700 EUR/year in financial savings, before counting admin time.
Need a professional website?
Kolonell builds websites that attract clients, optimized for the Sénégalese market. Free quote in 2 minutes.
Mini case study
Claire, CFO of an industrial mid-cap in London, faces a DSO of 58 days. She invests 48,000 EUR in a billing portal plus 800 EUR/month maintenance. Within 6 months, DSO drops to 34 days, freeing about 394,000 EUR of cash and saving 18 hours of chasing per month (about 6,500 EUR/year of time). The portal pays for itself in under 18 months on financial and admin gains alone.
FAQ
How much does a billing portal cost in 2026? Between 30,000 and 70,000 EUR depending on integrations (ERP, PSP) and reminder scenarios. An MVP (viewing + payment) starts under 35,000 EUR.
Which payment methods to integrate? Stripe for cards, GoCardless for recurring SEPA direct debit. Together they cover most B2B cases in Europe.
How much does DSO drop? Typically 15 to 30 days thanks to instant payment and automated reminders. The gain depends on your client mix and current terms.
Does the portal connect to my ERP? Yes, via API or connector. We sync invoices, due dates and payments to avoid any double accounting entry.
How long to go live? 12 to 18 weeks over 4-5 sprints. A first release (invoice viewing) can ship as early as week 6.
Let's scope your project. Billing portal 30,000-70,000 EUR, ERP + Stripe/GoCardless integration and automated reminders, delivered in 12-18 weeks: tell us your invoice volume and your ERP. 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.
