The verdict in three sentences
A custom tax and payroll filing portal costs between EUR 28,000 and 65,000 in Amsterdam in 2026, with a 4 to 7 month delivery and support around EUR 450 per month. The return doesn't come from the tool itself, but from cutting document collection time by 40 % and reducing late-filing penalties. For a firm managing 200 clients, the portal pays for itself in under 18 months.
What a filing portal does
The purpose: automate client document collection, orchestrate reminders before deadlines, and streamline filing via e-filing gateways. Here are the 2026 line items for Amsterdam.
| Module | Scope | Range (EUR) |
|---|---|---|
| Client portal & upload | Secure upload, mobile, categorisation | 7,000 - 16,000 |
| Collection workflow | Steps, approvals, statuses | 6,000 - 13,000 |
| Automated reminders | Email, SMS, tax deadlines | 4,000 - 10,000 |
| E-filing integration | VAT, payroll, statements | 7,000 - 16,000 |
| Compliance dashboard | Late tracking, completeness rate | 4,000 - 11,000 |
| Integration & UAT | Accounting API, migration, tests | 3,000 - 9,000 |
| Total project | Full portal | 28,000 - 65,000 |
ROI modelled on 200 clients
Assume 200 clients, 6 filing collections per year each, 45 minutes of admin per collection at EUR 50 an hour.
| Line | Before portal | After portal (-40 %) | Annual gain |
|---|---|---|---|
| Collection time | 900 h/yr | 540 h/yr | 360 h |
| Admin cost | 45,000 | 27,000 | 18,000 |
| Client late penalties | ~9,000 | ~2,800 | 6,200 |
| Satisfaction / retention | baseline | +5 points | indirect value |
| Total year-1 gain | - | - | ~24,200 |
For a EUR 50,000 project plus EUR 5,400 annual support, payback sits around 17 months, with recurring gains thereafter.
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Mini case study
Eva, director of a 240-client firm in Amsterdam, faces the annual scramble for documents before VAT and payroll deadlines. She pulls in 2 assistants during peaks. A custom portal at EUR 50,000, plus EUR 450 monthly support, automates reminders and collection, dropping admin time by 40 %. She saves EUR 18,000 in time and EUR 6,200 in penalties in year one, EUR 24,200, while making e-filing more reliable. Payback in about 17 months.
FAQ
Does the portal connect to e-filing? Yes, connecting VAT, payroll and statement submissions runs EUR 7,000 to 16,000 depending on flows; it's the line that most improves your deadlines.
How much collection time can you really save? A 40 % drop is realistic from the first campaign, thanks to automated reminders and direct client upload.
Will clients adopt the portal? Yes, if it's mobile and simple: auto-categorisation and SMS reminders raise the on-time completeness rate.
How long to go live? Between 4 and 7 months, with a usable collection portal from month 3.
What does maintenance cost? About EUR 5,400 a year (EUR 450 per month), including regulatory updates and enhancements.
Let's scope your project. Tell us your client count, filing types and peak periods, and we'll price the portal and its 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.
