The grantor of a scholarship or fellowship does not withhold tax unless the grant represents payment for services.
Grants representing payment for services are wages for withholding purposes.
The grantor must report them on a Form W-2. You may have to pay estimated tax if the grantor of a scholarship or fellowship does not withhold tax or withholds insufficient tax on the taxable part of your scholarship or fellowship grant. Your estimated tax is the total of your expected tax for the year minus your expected withholding and credits. Use Form 1040-ES, Estimated Tax for Individuals, to figure and pay estimated tax. You must have filed a return for the preceding tax year that covers all 12 months.