Why this matters
Many people start a side business while employed because it provides financial security. At the same time, that's exactly where typical conflicts arise: employment contracts, competition with your employer, rest and recovery, sick leave, working hours, and confidential information. Sorting through these points early means a calmer start and helps you avoid unnecessary friction.
Turn knowledge into a start plan
This guide explains one topic. Whether it is really a priority for you right now depends on your answers in the start plan.
Create start planThe basic idea: a side business is possible, but not without limits
Working as self-employed alongside your main job is not automatically prohibited. What matters is whether your employment contract, your employer's legitimate interests, or applicable legal requirements are affected.
The most important distinction is: does your contract simply require you to notify or get approval, or is there a genuine conflict with your main job? A small Etsy shop run on weekends is a very different situation from working for direct competitors of your employer.
This page does not replace a review under employment law. It shows you which questions to ask before you start, so you don't accidentally put your employment relationship at risk.
Read your employment contract first
Check whether your employment contract contains a secondary employment clause (Nebentätigkeitsklausel). Some contracts require that paid secondary activities be disclosed or approved in advance. This does not automatically mean your side business is prohibited.
What matters is the exact wording. Does it only require you to notify your employer? Do you need their consent? Are certain types of work excluded? Are there specific rules covering secondary jobs, self-employment, competitive activities, or working hours?
If you are unsure, a written, matter-of-fact enquiry is often better than starting quietly. Describe the activity neutrally, be realistic about the scope, and clearly distinguish it from your main job.
Avoiding competition and conflicts of interest
Things become particularly sensitive when your side business operates in the same market, serves similar customers, offers similar services, or draws on information from your main job. In those cases, your employer may have a legitimate interest that is affected.
Ask yourself: Are you selling to your employer's customers? Are you using internal knowledge, contacts, documents, software, data, or work equipment? Could your offering be seen as competing with your employer?
The closer your side business is to your employer's line of work, the more careful you should be. In such cases, getting a professional assessment is often wiser than making a quick gut decision.
Working hours, rest, holidays, and sick leave
Even if your side business is officially permitted, it must not practically undermine your performance in your main job. Persistent exhaustion, scheduling conflicts, insufficient rest, or working on your side business during your main working hours can all become a problem.
The key lesson here is: plan not just revenue and tasks, but also your energy. When will you realistically work on your side business? How will you protect your sleep, weekends, holidays, and recovery time? What happens when a client deadline and pressure from your main job hit at the same time?
Sick leave is especially critical. If you are signed off sick, you should not carry out any activity that contradicts your recovery or creates the impression that your incapacity for work in your main job is not being taken seriously.
A good notification is specific and calm in tone
If you need to — or want to — inform your employer, a short, clear description helps: What will you be doing? For whom? How much? When? How will you ensure that your main job, working hours, confidentiality, and your employer's interests are not affected?
Avoid marketing language. Your employer does not need to evaluate your vision — they need to understand whether any legitimate interests are at stake. The more clearly you describe the scope, the boundaries, and the absence of conflicts, the less room there is for objections.
Keep a record of the response. If consent is required, a written confirmation is far more reliable than trying to recall a conversation from a hallway chat.
Quick checklist
- Have you read your employment contract and any secondary employment clause?
- Is notification or approval required?
- Is there any overlap with your employer's customers, market, data, or services?
- Can you explain the scope, timing, and boundaries in a straightforward way?
- Are your main job, rest time, sick leave, and working hours kept clearly separate?
- Do you need a professional review before you start?
Common mistakes
- Starting a side business quietly even though the contract requires notification or approval.
- Treating direct competition with your employer as a harmless extra income stream.
- Using work equipment, contacts, or internal knowledge from your main job.
- Underestimating the time commitment and ending up permanently overloaded.
- Relying on verbal consent when written clarity would be far more practical.
Frequently asked questions
Do I always have to inform my employer?
Not as a blanket rule. What matters is your employment contract, any secondary employment clauses, competition, working hours, rest and recovery, and your employer's legitimate interests.
Can my side business compete with my employer?
This can be problematic. Activities that directly compete with your employer or harm their interests should be reviewed particularly carefully.
Should I get consent confirmed in writing?
If consent is required, or if you want to avoid any ambiguity, getting it in writing is often the sensible approach. A binding legal assessment, however, is a matter for qualified employment law advice.
What this guide can and cannot do
This guide helps with
- put together a neutral list of questions tailored to your situation
- help you draw a clear line between your side business and your main job
- draft a matter-of-fact message to your employer
- highlight typical conflict points to watch out for
This guide does not replace
- provide a legally binding interpretation of your employment contract
- decide whether your employer's consent is required
- replace qualified employment law advice