The 4-part model: why we separate development from maintenance

The problem

A typical agency sells you a monthly fee. “For €1,500 a month we build your website, maintain it and include changes.” It sounds good. The reality is different: the fee is an opaque box containing development, hosting, emails, support and enhancements on one line. You do not know what you are paying for or why. When you ask for a change, it turns out “it is not covered by the fee” or “must be billed separately”.

The result is that the client loses trust. They do not know whether the price is fair, whether changes are urgent or invented, whether maintenance is real or passive income for the agency. When they want to leave, they discover nothing is documented and the “fee” was actually a lock.

SOM-OS does not work that way. We invoice 4 separate items, each with its own reason, frequency and receipt. No opaque box. No single fee. No invoice surprises.

The 4 items

1. Development — a one-off payment

This is what we build. The website, app, system or AI agent. A fixed price for a defined scope, paid once on delivery. No recurring fee hidden inside development. What we agree is what you pay.

Development includes design, code, deployment, initial team training and a 30-day warranty to fix anything not working as planned. After those 30 days, item 3 begins.

2. Usage costs — at cost, with a receipt

Everything with a usage cost that is neither development nor maintenance: hosting, domains, emails, third-party APIs, AI tokens, SMS and storage. We pass it on at cost — without markup — with the provider’s receipt so you see exactly what you pay.

If your app uses the OpenAI API and spends €47 a month on tokens, your invoice has a €47 line. Not €80. Not “AI services €150”. €47, backed by the OpenAI receipt.

This is inconvenient for the agency — because there is no margin — and transparent for the client. That is why we do it.

3. Maintenance — €30–110/month, decreasing

Maintenance keeps the system working without you doing anything: security updates, patches, monitoring, backups and a monthly log review. It is not development. It is prevention.

It costs between €30 and €110 a month depending on the system’s size. It is decreasing: the first 3 months cost the maximum because there is more to review. After a year, it drops. After two years, it drops further. The idea is that a well-built system needs less maintenance over time, not more.

If an agency charges the same maintenance in year 1 as in year 5, something does not add up. Either they maintain nothing or charge a disguised margin.

4. Enhancements — €60–500 per task

Enhancements are changes, improvements and new features you request after the system is in production. “Add a field to the form”, “connect this ERP”, “create a new metrics dashboard”. Each enhancement has a fixed price per task, between €60 and €500 depending on scope.

There is no bank of hours. No “you have 4 hours left this month”. Each request is quoted, confirmed and invoiced on delivery. You decide whether it is worth the price before we start.

Why a bank of hours does not work

A bank of hours is the favourite model of an agency wanting recurring income without visible work. It sells “20 hours a month” for €1,200. The client does not know how many hours were actually worked. If you request nothing that month, the agency keeps the hours. If you request more than expected, it bills extra.

The incentive is distorted: the agency earns more by working less. The client cannot audit the time because “hours” are an opaque unit nobody measures the same way.

• Development: one-off payment, fixed price, no recurring fee.
• Usage costs: at cost, with the provider’s receipt, no markup.
• Maintenance: €30–110/month, decreasing, no enhancements included.
• Enhancements: €60–500 per task, fixed price before starting.

Four items, four receipts, four reasons. No opaque box, no single fee, no surprises on month 14’s invoice.

What you gain

With this model, you always know what you are paying for and why. If there are no enhancements that month, you do not pay for enhancements. If your system has been stable for two years, maintenance drops. If usage costs rise, you see it on the receipt and can decide whether to optimise.

Most importantly, if you move to another agency, you take everything documented. No technical lock disguised as a fee. The code is yours, the data is yours, the deployment is yours. We charge to build and maintain, not to retain.

To see this model applied to a real case, look at Nemus: a single custom app replacing 5 tools, with the 4 items clear from day one.