Side Jobs Aren't Banned, Your Contract Just Wasn't Read
Side Jobs Aren't Settled by One Sentence
A weekend freelance project lands. An old friend wants to spin up "a small SaaS." Or the evenings freed up by AI tooling produce a personal app worth shipping. The first reflex is "how would the company find out, would it be a problem?" The answer usually sits further from intuition than expected: side jobs aren't banned by one clause in the contract, they're surrounded by scattered ones.
In Türkiye, almost no employment contract explicitly bans moonlighting. Instead of bans, contracts use conditions and assignment. You may need written permission before starting a paid side project; intellectual property created during work hours may already be assigned to your employer; the non-compete clause may cover even your own personal product. None of these makes a side job impossible, but ignoring all three together usually ends in termination without severance.
This post isn't about how to do a side job, but about where to look in your contract before you start one. For the income strategy itself, see freelance vs full-time and working remote for foreign companies. The focus here is the legal surface of side work.
Three Clauses Worth Reading
A software engineer's contract has three sections that govern side work. The names vary but the meaning is consistent.
Loyalty and permission. Usually phrased as "the employee shall not perform paid work for any other person or institution without written consent of the employer." If you start a side job without reading this clause, the employer can use it as cause for termination once they find out - without severance. Unpaid open-source contributions, personal blogs and conference talks may fall outside this scope; the keyword is "paid."
IP assignment. This clause assigns ownership of all code, documentation and ideas produced during work hours, on company equipment or using company resources to the employer. Some contracts limit it to "within the scope of work." Others extend to "anything related, produced during the term of employment." The second version puts even your evening side project ownership in dispute.
Non-compete. Restricts working at a competing company for a defined period after leaving. The definition of "competitor" for software engineers is fuzzy; phrases like "same sector or similar product" can cover the entire SaaS market. This clause also affects what you can do as a side job while still employed: the company can argue "you're building a potential competing product for our customer."
All three sit in different paragraphs of the same contract. They're not reviewed individually at signing - they're signed as part of the standard HR package. They all surface together when side work appears.
"Code I Write After Hours Is Mine" - The Trap
The most common misconception: "code I write after eight in the evening is mine." The contract usually doesn't draw the line by clock. The decisive factors are three different criteria:
- Was company equipment (laptop, phone) used?
- Did company information (customer data, internal docs, closed-stack knowledge) leak in?
- Is it in direct competition with the company's scope of business?
If the answer to any of the three is "yes," the fact that the code was written after hours becomes irrelevant. Courts apply the same logic; an employment contract doesn't enumerate hours, it governs the whole relationship.
Practical consequence: a side job needs personal laptop, personal accounts (GitHub, email, cloud) and a domain outside the company's scope of business. These three are non-negotiable preconditions. Starting a side job without separating them opens the door to "you didn't really do this on your own time, did you?"
Ask for Written Permission, or Not?
Most engineers prefer to keep side jobs hidden. The logic: "they'd say no if I asked, so why ask." Sometimes correct, sometimes not.
The advantage of asking in writing: if permission is granted, the company cannot later claim a loyalty or competition breach. There's a written record. If denied, at least you know the boundary; better than getting caught later.
The disadvantage: a denial closes the door. Once the company says "no," doing it secretly afterwards is a double offence. A note like "this person asked for side work, was denied" can resurface in a performance review against you.
The decision becomes clearer with three questions:
- Does the side job intersect with the company's customer base, product or technology? If yes, permission would be denied anyway and doing it secretly is twice as risky. Changing the side project is the only option.
- Does the company culture treat side projects as normal? Some companies (especially scale-up size) have IP policies that actually allow side work; the formality of asking is enough.
- Is the side job income visible on the tax side? If you set up a sole proprietorship, your VAT filings leave a trail. If the company really investigates, they'll see it. So "they won't notice" is a weak assumption when income is documented.
Rule of thumb: if the side job isn't in the same scope of business and the income is tax-visible, asking in writing is defensible. Otherwise, change the side project.
Open Source and Conferences - Grey Zone
For engineers, side work isn't just freelance projects. Personal GitHub projects, open-source contributions, blog posts, conference talks, training videos - all sit in the contract's grey zone.
Open-source contributions. PRs to a project outside the company technically need permission in most contracts, but in practice it's rarely tracked. The risk: if you contribute to a project the company itself uses (e.g., the company runs Spring Boot, you push a PR to Spring), the IP assignment clause may activate. The company can argue "you developed this commit during our process."
Blogs and conferences. Usually unpaid, so not "work" in the strict sense, but paid speaking or sponsored content is different. Sponsorships count as income, the loyalty clause activates. Solution: separate the income source, ask for written permission if you write sponsored content.
Training and courses. Udemy, YouTube monetization, closed training platform sales - all income. If the company says "the topic is in our domain," the non-compete clause comes into play. Topic selection matters: courses on subjects far from your company's stack and customer segment are safer.
In all three cases, the practical rule: income means written permission, no income means topic control.
Tax Burden - Sole Proprietorship or Off the Books?
Earning side income and ignoring the tax side is the easiest mistake. Two years later, a letter from the tax office arrives; back income tax, late-payment interest and penalty are assessed. At that point, if you also didn't ask the company for permission, you face problems on three fronts simultaneously.
Three structures exist for side income tax in Türkiye:
| Structure | Advantage | Disadvantage |
|---|---|---|
| Sole proprietorship (basic / business ledger) | Low setup cost, VAT filing trackable | Above ~1M TRY annual income, switches to "real" basis, tax burden rises |
| Limited company (LLC equivalent) | Expense flexibility, BES/SGK advantages | 8-10K TRY annual accounting + registration cost |
| Off the books (no invoice) | Easy short-term | Under audit, all income is back-assessed with penalty; reputation risk |
Sole proprietorship is the most common choice for engineers. VAT is 20%, income tax follows progressive brackets. For annual side income in the 200-300K TRY band, sole proprietorship is enough; above that, LLC starts to make sense.
A key point: you can open a sole proprietorship while your SGK record is active at the main employer. Bağ-Kur and SGK can't run simultaneously, but when SGK is active and a sole proprietorship is opened, Bağ-Kur is automatically deactivated. Only the tax obligation arises, no extra premium.
Another tax dimension: if side income flows through your bank statement and your company HR has authority to check bank records (rare but possible), it won't stay hidden. Tax filings are always traceable backwards; "they haven't noticed yet" is a weak defence.
The Hard Clauses You'll Encounter
When side work is on the table, three clauses cause the most friction:
"The employee undertakes to dedicate all intellectual effort to the company throughout the term of employment." This clause, with the phrase "all intellectual effort," is broad enough to cover even a piece of code written in the evening. Legal interpretation tends wide. Pay attention to this one when signing; it's negotiable.
"The employee assigns to the company all intellectual property developed during, or prior to, performance of duties." The word "prior to" is dangerous - even side projects you started before joining can transfer to the company. Solution: when signing, list existing side projects in writing as exclusions. HR usually doesn't push back.
"For X months following termination of employment, the employee shall not work directly or indirectly in the field where the company operates." The non-compete clause. In Türkiye, the Court of Cassation accepts at most 2 years and requires concrete geographic limits. Overbroad clauses are often invalid, but you'd have to litigate. While doing side work, this clause adds threat surface.
All three are negotiable. Asking for "IP only within the scope of work" and "non-compete 6 months and within Istanbul" is legitimate at signing. HR is usually flexible; standard templates are expected to be signed but objections aren't rejected.
Quick List If You've Decided
Once the decision is made, the steps are concrete:
- Read the loyalty, IP and non-compete clauses individually, word by word
- Check whether the side project intersects with the company's scope of business, customer base or tech stack
- If no intersection, ask for written permission; if yes, change the project
- Choose the tax structure: under 200K TRY annual, sole proprietorship is enough
- Don't mix company equipment into side work at all; separate laptop, separate GitHub, separate email
- Work with an accountant from the first invoice; cleaning up retroactively in year two is expensive
- If side income grows, remember severance and notice period implications - see the resignation guide, since transitioning to full-time on the side opens different contract questions
Side jobs aren't banned, but done without permission they're expensive. Reading the contract takes an hour; hiring a lawyer two years later is a thousand-hour ordeal. getSalary's 2026 data shows side income adds 20-40% on top of base salary on average; that's worth taking the risk for, but taking the risk without seeing it doesn't produce value.