The verdict in three sentences
For an Amsterdam services company invoicing 900 B2B customers, a customer portal with iDEAL and SEPA Direct Debit payments and a two way sync with Exact Online costs 25,000 to 60,000 EUR with a local agency (2026 market ballpark). The figure that justifies the spend is DSO dropping from 58 to 38 days, because customers who can open an invoice and pay it in two clicks pay earlier than those digging a PDF out of an inbox. Exact Online integration is where projects succeed or fail: if payments are not matched automatically, your finance team retypes everything and the portal becomes another place to check.
What the portal includes and what it costs
Dutch B2B buyers are used to paying by bank, so card payments matter less than in many markets. What they want is a clear statement, the right invoice PDF for their accounts payable team, and a payment method their finance controller already trusts.
| Module | Scope | Cost (EUR, 2026 market ballpark) |
|---|---|---|
| Customer workspace | Invoices, credit notes, statement, several users per customer, UBL download | 5,000 to 11,000 |
| iDEAL payments via a PSP | Pay one or several invoices, automatic receipt | 3,000 to 7,000 |
| SEPA Direct Debit mandates | Online mandate signup, collection on due date | 3,500 to 8,000 |
| Automated reminders | Before due date, then a schedule you control, in Dutch and English | 3,000 to 6,000 |
| Two way Exact Online sync | Invoices to the portal, matched payments back to the ledger | 6,500 to 16,000 |
| Credit control dashboard | DSO, aged debt, at risk accounts | 2,000 to 6,000 |
| Testing and rollout | Pilot with 25 customers, finance team onboarding | 2,000 to 6,000 |
| Total | 25,000 to 60,000 |
PSP fees for iDEAL are usually a fixed amount per transaction and SEPA Direct Debit fees are low as well; both vary by provider and volume, so compare offers from two or three payment service providers before you commit. Card payments are worth adding only if you have foreign customers.
As a nearshore option, Kolonell's prices for a medium application run from 6,100 to 10,670 EUR (4,000,000 to 7,000,000 FCFA), with Standard maintenance at 114 EUR per month. Delivery is in English and the team works one to two hours behind Amsterdam time.
Expected impact on collections
The trajectory below is a realistic 6 month target for a firm moving from manual follow up to a self service portal. Treat it as a project objective, not a promise.
| Metric | Before | After 6 months (target) |
|---|---|---|
| DSO | 58 days | 38 days |
| Invoices paid on time | 48 % | 70 % |
| Hours spent chasing per week | 10 | 3 |
| Copy invoice requests per month | 90 | 15 |
| Unreferenced bank transfers | 22 % | 5 % |
| Customers on SEPA Direct Debit | 0 % | 20 % of recurring contracts |
Dutch and EU rules on late payment in commercial transactions set default payment terms and allow statutory interest and collection costs. Check the official texts or your accountant for the exact terms that apply to your contracts; the portal helps you enforce them consistently.
Decisions to make before requesting a quote
Decide whether Direct Debit is offered to all customers or only to recurring contracts, how often Exact Online should sync (every 15 minutes is plenty for 900 customers), and whether large accounts with several entities need one login per entity. Also decide whether e-invoices in UBL format should be sent by the portal or stay with your accounting software.
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Illustrative example: Daan, CFO of a facility services company in Amsterdam Zuidoost, bills 14,000,000 EUR a year to 900 customers, about 38,400 EUR per day. Bringing DSO from 58 to 38 days frees 20 days of revenue, roughly 768,000 EUR of working capital. At an assumed 7 % on his credit line, that saves about 53,800 EUR a year, plus 7 hours of chasing per week over 46 weeks at 55 EUR an hour, 17,700 EUR a year. A 45,000 EUR portal pays back in about 8 months (45,000 / 71,500 per year).
FAQ
How much does a customer portal with online invoice payment cost in Amsterdam?
Expect 25,000 to 60,000 EUR with a local agency, depending on the depth of the Exact Online sync and payment methods (2026 market ballpark). A view only portal without payments can come in around 10,000 to 15,000 EUR.
How long does it take?
Plan 8 to 12 weeks, including a 2 week pilot with about 25 customers. The Exact Online sync alone usually takes 3 weeks.
iDEAL or SEPA Direct Debit?
Offer both: iDEAL for one off invoices, Direct Debit for recurring contracts. Firms that move 20 % of recurring customers to Direct Debit typically see those invoices paid on the due date every month.
Will customers actually log in?
They do when every reminder contains a direct link to the invoice and payment button. In a typical rollout, 40 to 60 % of active customers log in at least once in the first 3 months.
Can the portal send e-invoices?
Yes, it can expose UBL files for each invoice so accounts payable teams import them directly. Allow 2,000 to 4,000 EUR extra if you want the portal to handle e-invoice delivery itself.
Let's scope your project. Share your customer count, Exact Online setup and preferred payment methods, and we will price a portal with an 8 to 12 week 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.
