The verdict in three sentences
A custom application to automate the quote → purchase order → invoice → dunning cycle costs between 12,000 and 40,000 EUR net in 2026, delivered in 6 to 12 weeks. The return comes from 12 to 20 admin hours saved every month and a collection period (DSO) cut by roughly 25%. Below 12,000 EUR net you are funding a fragile no-code stack; above 40,000 EUR net you enter heavy ERP integration territory.
What the project covers and what it costs
The classic scope for a 10-to-50-employee SME in London includes templated quotes, automatic conversion to invoice, e-signature, scheduled dunning and accounting sync. Here are the 2026 ranges per work package.
| Work package | Indicative timeline | 2026 cost (EUR net) |
|---|---|---|
| Discovery + UX mockups | 1-2 weeks | 2,000 - 4,500 |
| Quote engine + product catalogue | 2-3 weeks | 4,000 - 9,000 |
| Invoice conversion + legal numbering | 1-2 weeks | 2,500 - 6,000 |
| E-signature + auto dunning | 1-2 weeks | 2,000 - 5,500 |
| Accounting / CRM integration (API) | 1-3 weeks | 3,000 - 10,000 |
| Testing, training, go-live | 1 week | 1,500 - 5,000 |
A Starter build (quote-invoice + dunning, no deep accounting integration) fits within 12,000 to 18,000 EUR net. A complete build with a Xero/Sage/QuickBooks connector and qualified signature climbs to 30,000 to 40,000 EUR net.
E-invoicing 2026: an ROI accelerator
The wider move to e-invoicing across Europe makes the investment even more relevant. Being able to issue and receive structured electronic invoices avoids double entry and format rejections, so automating upstream pays off twice.
| Metric | Manual process | Automated process |
|---|---|---|
| Time to create one invoice | 8-12 min | 30-60 s |
| Data-entry error rate | 4-6% | < 1% |
| Average collection period (DSO) | 52 days | 38-40 days |
| Processing cost per invoice | 9-14 EUR | 2-4 EUR |
| Reminders sent on time | ~60% | ~98% |
At 150 invoices per month, moving from 11 EUR to 3 EUR per invoice saves 1,200 EUR every month, about 14,400 EUR a year: the tool pays for itself in under a year.
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Mini case study
Claire, CFO of a 32-person industrial SME in East London, issues 180 quotes and 140 invoices a month. Her team spends 18 hours monthly on manual entry, conversion and dunning. She invests 22,000 EUR net in a custom app (quote engine, invoice conversion, multichannel dunning, accounting connector), plus 450 EUR/month maintenance.
Over 12 months: 18 hours saved per month valued at 35 EUR/hour = 7,560 EUR/year of admin time, plus a DSO drop from 52 to 39 days freeing roughly 28,000 EUR of cash. Total first-year cost: 22,000 + 5,400 = 27,400 EUR net. Time savings alone repay 28% of the project in year one; the freed cash covers the rest.
FAQ
How much does maintenance cost after delivery? Application maintenance runs between 300 and 800 EUR/month in 2026 depending on integration complexity and support level. It covers fixes, minor evolutions and compliance updates.
How fast does it pay back? For an SME handling more than 100 invoices/month, break-even usually lands between 8 and 14 months, combining time saved and freed cash.
Can you connect my existing accounting software? Yes. Xero, Sage, QuickBooks and Pennylane expose APIs. The connector represents 3,000 to 10,000 EUR net depending on API richness and data mapping.
No-code or custom to start? For fewer than 50 invoices/month, a no-code stack at 50-100 EUR/month may be enough. Beyond that, custom becomes cheaper over 3 years and far more robust.
How long until go-live? Expect 6 to 12 weeks from discovery to go-live, team training included.
Let's scope your project. Share your monthly quote and invoice volume, your accounting software and an indicative budget, and we will price your quote-to-invoice automation. 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.
