Graduate study in the United States is frequently funded through assistantships rather than paid for directly. The arrangement is an employment relationship, and its terms explain most of what follows.
The package has two separate components
A typical offer combines tuition remission, which cancels some or all of the tuition charge, with a stipend paid across the academic year for defined work.
These are budgeted separately by the institution. A student can hold remission without a stipend, or a stipend without full remission, and offers vary widely between departments.
Fees are the common gap. Remission often excludes mandatory fees, health insurance charges or summer terms, which can amount to a meaningful out-of-pocket sum.
Teaching and research assistantships differ in kind
A teaching assistantship attaches to a department's instructional needs: leading sections, grading, holding office hours. The workload follows the academic calendar and is relatively predictable.
A research assistantship is usually funded by a grant held by a faculty member, and the work is the project's work, which may or may not overlap with the student's own thesis.
Overlap is the variable worth examining. Research assistantships that advance the student's dissertation effectively pay for time already needed; those that do not compete with it.
Funding sources determine how secure the position is
Departmental teaching lines depend on enrollment. Grant-funded research lines depend on the grant continuing, and grants end on schedules set before the student arrived.
Multi-year written guarantees are more valuable than verbal assurances of ongoing support, and the difference frequently becomes apparent only in later years of a program.
Applicants can reasonably ask how many years of funding are committed in writing, and what has happened historically to students in the same program.
Hours are nominal and the real workload varies
Assistantships are typically described as a set number of hours per week. Actual demands fluctuate with grading periods, experiment schedules and the supervising faculty member's practices.
Because the supervisor also assesses academic progress, the boundary between employment and study is unusually soft, and disagreements are harder to raise than in ordinary jobs.
Many campuses have graduate student unions or ombuds offices, and the protections available depend on the institution and on state law governing public and private employers.
The financial comparison is not simply free tuition
Assistantships are usually compatible with modest additional funding but often restrict outside employment, which limits alternative income during the program.
Stipends are taxable income and remission may be treated differently depending on the type of award, so the net position is worth checking with a tax professional.
Comparing offers means comparing stipend against local cost of living, fee coverage, years guaranteed and expected time to completion, rather than the headline word funded.