The verdict in three sentences
In 2026, a custom customer billing portal is budgeted between 25,000 and 65,000 EUR, depending on payment methods, accounting integration and dunning automation. Its real ROI is not convenience but a reduction in DSO (days sales outstanding) of 20 to 35%. For an SME billing several million euros, that frees tens of thousands of euros in cash within the first year.
The features that set the price
A billing portal combines invoice viewing, online payment, dunning and accounting sync. Here are the blocks and their 2026 order-of-magnitude cost.
| Feature | Scope | Cost 2026 (EUR) |
|---|---|---|
| Invoice space | Viewing, PDF, history | 5,000 - 10,000 |
| Card payment (Stripe) | Card, 3D Secure, receipt | 4,000 - 7,500 |
| SEPA direct debit | Mandates, schedules | 4,500 - 9,000 |
| Automated dunning | Reminder scenarios, email/SMS | 4,000 - 8,000 |
| Accounting integration | Sage, Cegid, QuickBooks, export | 6,000 - 14,000 |
| CFO dashboard | Outstanding, DSO, aging balance | 4,000 - 7,500 |
A portal focused on viewing + card payment starts around 25,000 EUR. With SEPA, automated dunning and real-time accounting integration, it reaches 50,000 to 65,000 EUR.
The collections ROI
The core value of a billing portal is financial. Every day of DSO saved improves cash. Here is the estimated impact by annual revenue, for a 25% DSO reduction.
| Annual revenue | DSO before | DSO after (-25%) | Cash freed |
|---|---|---|---|
| 2,000,000 EUR | 60 d | 45 d | ~82,000 EUR |
| 5,000,000 EUR | 55 d | 41 d | ~192,000 EUR |
| 10,000,000 EUR | 50 d | 37 d | ~356,000 EUR |
| 20,000,000 EUR | 45 d | 34 d | ~603,000 EUR |
Even at the low end, the cash freed far exceeds the portal's cost within the first year.
Mini case study
Nadia, CFO of an IT services SME in Bordeaux (revenue 6,000,000 EUR), faces a 58-day DSO and two accountants spending a third of their time on manual reminders. She invests 48,000 EUR in a portal with card/SEPA payment, automated dunning and Cegid integration. Within six months, DSO drops to 43 days (-26%), freeing about 215,000 EUR in cash, and dunning automation saves the equivalent of 0.4 FTE (~16,000 EUR/year). The portal pays back in under three months on the cash effect alone.
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FAQ
How does a portal actually reduce DSO?
By enabling immediate online payment, sending graduated automated reminders, and removing friction (lost invoice, wrong IBAN). A DSO moving from 55 to 41 days mechanically frees cash.
Should I offer both card and SEPA?
SEPA is ideal for recurring payments and cheaper in fees; card via Stripe suits one-off payments. Offering both maximizes the online payment rate.
Does the portal integrate with my accounting software?
Yes, via API or connectors: Sage, Cegid, QuickBooks. Integration costs 6,000 to 14,000 EUR but removes manual reconciliation and improves data accuracy.
How much time is saved on dunning?
An SME automating reminders often saves 0.3 to 0.6 FTE of accounting time, i.e. 12,000 to 24,000 EUR/year, while accelerating collections.
Is payment data secure?
Yes: the portal never stores card numbers (handled by Stripe, PCI-DSS certified) and SEPA mandates are encrypted. You stay compliant without managing PCI complexity.
Let's scope your project. Share your revenue, current DSO and accounting software, and we will frame a billing portal between 25,000 and 65,000 EUR with a quantified cash ROI. 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.
