TL;DR: Many funded assistantship and fellowship appointments include an explicit cap on outside work hours (often around 8–10 hours per week) as a condition of the funding, not just a general expectation. International students on F-1 or J-1 visas face separate, stricter federal rules on any off-campus work. Check the actual appointment letter or funding terms before assuming a side gig is fine, rather than assuming it's a personal decision with no institutional constraint.
Why this isn't purely a personal choice
A teaching or research assistantship is a paid position with a specific expected time commitment, not just a stipend with no attached obligations. Many universities cap total outside employment (including on-campus jobs beyond your assistantship) as an explicit term of the appointment, on the reasoning that a full-time assistantship plus significant outside work isn't compatible with the expected effort.
What to actually check before taking on outside work
- Your appointment letter or offer letter, which often states an explicit outside-work-hour limit as a condition of the assistantship or fellowship
- Your department's or graduate school's general policy, since some limits are set at the university level rather than per-appointment
- Your specific funding source's rules, if funded by an external fellowship or a federal training grant, which may have its own restrictions independent of university policy
International students: a materially different situation
F-1 and J-1 visa holders face federal (not just university) restrictions on employment, generally limited to on-campus work during the academic year unless specific authorization (like Curricular Practical Training or Optional Practical Training) has been granted for off-campus work. Violating these terms carries immigration consequences, not just a funding or disciplinary issue at the university level. International students should check with their university's international student office before taking on any outside work, including remote freelance work, since some forms of unauthorized "work" are broader than students expect (for example, unpaid work can sometimes still count as work under immigration rules).
Forms of income that commonly fall into gray areas
- Freelance or contract work (tutoring, freelance writing, consulting) — often allowed for domestic students within hour limits, but frequently restricted or requiring authorization for international students
- Passive income (a rental property, investment income, an Etsy shop that runs with minimal ongoing time) — generally treated differently from active work-for-pay, but "minimal ongoing time" is doing a lot of work in that sentence, and it's worth getting clarity rather than assuming
- Paid research collaborations outside your own lab — sometimes require advisor or department sign-off even if otherwise permitted, since it can raise conflict-of-interest questions
A reasonable way to approach this
Before starting any outside income source, however small: read your actual appointment letter for an hours cap, ask your graduate program coordinator if the terms are unclear, and — for international students specifically — check with the international student office before assuming a form of income is fine just because it seems minor or informal.
The cost of asking first is a short conversation. The cost of not asking, for a funded position or a visa status, can be considerably larger.