A side hustle in Germany runs into the same machinery as everything else: the Finanzamt wants its share, and there are rules about declaring it, taxing it, registering it, and even whether your day-job employer gets a say. Many people start earning on the side, freelancing in the evenings, a weekend gig, a small business, without realising that a second employed job can be taxed at the punishing tax class 6, that freelance side income must be registered, or that their employment contract may require them to disclose it. None of it stops you earning extra, but doing it without understanding the tax and the rules invites trouble. Set it up right and the side income is clean and worthwhile.
This guide covers side income in Germany: declaring it, the tax-class-6 trap on second jobs, freelance versus minijob, registration, and what your employer can say. Earn on the side without nasty surprises.
You must declare it
Start with the rule that admits little exception: side income generally must be declared.
Side income, from a second job, freelancing, or a side business, must be declared to the tax authorities and reported on your tax return. There can be small allowances for minor income, but in general additional income is taxable and must be declared.
The serious part: failing to declare taxable side income is tax evasion. So this is not optional or a grey area, taxable side earnings must be reported properly on your annual tax return. Germany takes undeclared income seriously, and the consequences of being caught (back taxes, penalties) far outweigh the tax you would have paid.
So the foundational principle: whatever you earn on the side, declare it. The rest of this guide is about doing that correctly, the right tax treatment, registration, and employer rules, so your side income is fully legitimate. Do not be tempted to keep side earnings "off the books"; the German system expects them declared, and the risk of not doing so is real.
The tax-class-6 trap on second jobs
A nasty surprise for people taking a second employed job: it is typically taxed at tax class 6 (Steuerklasse 6), the highest-withholding class.
Why: your tax-free allowances are used by your main job, so the second job gets no allowance and is taxed at the heaviest rate from the first euro. This means heavy withholding on the second job, your take-home from it can feel surprisingly small.
The reassurance: your annual tax return reconciles the total. Class 6 over-withholds during the year, but filing recalculates your true overall tax, so you often get some back. Still, the in-year cash flow from a second employed job is reduced by the class-6 withholding (the tax-class system explains the mechanics).
The tax-friendly alternative: a minijob (up to €556/month) alongside a main job is treated more favourably and is largely tax-free for you (the employer pays a flat rate). So if you want to earn a bit extra through employment, a single minijob is far more tax-efficient than a regular second job at class 6 (see the minijob rules). A second minijob on top, or other additional employment, gets added and taxed (often class 6).
So for employed side income: one minijob = tax-friendly; a regular second job = class 6 = heavy withholding (reconciled annually). Choose the minijob route for tax-efficient extra employment income where it fits.
Freelance vs minijob, and registration
Side income comes in two main forms, taxed and administered differently:
Employed side income (a second job or minijob):
- Handled through employment (the employer manages tax/withholding)
- No registration needed by you
- Minijob = tax-friendly; second regular job = class 6
Freelance/business side income (freelancing, a side business):
- Generally requires registering the activity with the Finanzamt (and possibly the trade office for a Gewerbe)
- Getting a tax number and invoicing properly (see freelance invoicing and VAT)
- Often using the Kleinunternehmer rule for small side businesses (skip charging VAT below the threshold)
So the registration question depends on the type: freelance/business side hustles need registration (Finanzamt, tax number, invoicing, possibly VAT or Kleinunternehmer); additional employment does not (the employer handles it). This is a key fork: if your side income is self-employed (you invoice clients), you must register it; if it is employment (you are paid as an employee), you do not.
For a self-employed side hustle, the setup mirrors a freelancer's, just on a smaller, part-time scale: register, get the tax number, invoice properly, likely as a Kleinunternehmer given the small turnover, and declare the profit on your tax return. Get this right from the start so your side business is legitimate.
What your employer can say
A question side-hustlers worry about: can my employer stop me? The answer: sometimes, within limits.
- Your contract may require you to disclose or get approval for side work
- Employers can object to side jobs that compete with them, harm their interests, or breach working-time limits across both jobs
- But a blanket ban on any side activity is generally not enforceable
So your employer cannot simply forbid all side work, but they can restrict side jobs that conflict with your main job (competing, harming the company, or pushing your total hours past working-time limits). And your contract may require you to disclose or seek approval for side work.
The practical steps:
- Check your contract for a side-work / secondary-employment clause
- Where required, inform or get approval from your employer
- Avoid side work that competes with your employer or breaches working-time limits across both jobs
So you generally can have a side hustle, but follow your contract's disclosure rules and avoid conflicts (competition, working-time breaches). A non-competing side gig that you have disclosed where required is normally fine; a secret competing business, or one that pushes your hours over the legal limit, is asking for trouble.
The bottom line: side income in Germany must be declared (it is taxable), a second employed job hits class 6 (heavy withholding, reconciled annually) while one minijob is tax-friendly, freelance/business side income needs registering with the Finanzamt (and proper invoicing, likely as a Kleinunternehmer), and your employer may require disclosure and can object to conflicting side work but not ban it outright. Set it up correctly, declare it, register if self-employed, follow your contract, and your side hustle is a clean, legitimate extra income.
What to do this week
- Declare any side income on your tax return, it is taxable (small allowances aside), and not declaring it is tax evasion.
- For employed extra income, prefer one minijob (largely tax-free) over a regular second job (taxed at heavy class 6); for freelance/business side income, register with the Finanzamt and invoice properly, likely as a Kleinunternehmer.
- Check your employment contract for side-work disclosure/approval rules, and avoid side jobs that compete with your employer or breach working-time limits across both.
