Non-service stipend +hourly wage income tax = ?
Thank you for taking the time to read over my inquiries.
I am a 4th year biomedical graduate student who receives an annual living stipend bi-weekly, which is not taxed, and I also earn an hourly wage job part-time at a tutoring center which is taxed. The institute I receive my stipend from does not provide a 1099-MISC, 1098-T, or W-2 as this is considered a non-service stipend. Therefore, the income is not reported. However, they encourage us to report the income on our returns and to make quarterly payments, in which case I do. I am still not certain why taxes still needed to be paid on a living stipend, in which the amount of money is already very low and is not reported, but in any case I pay the expected amount for safe measure.
Last year I acquired a part-time, hourly paying, tutoring job in which I earn $70-$400 biweekly. Even though I have claimed 0 on my W-4, the taxes taken out are negligible, presumably because it does not earn me enough income to reach a taxable income threshold. However, this year I filed my taxes in turbotax and have surprisingly owed a couple hundred dollars from what I suspect is underpayment from the hourly job, which does not take into account the stipend I receive. Although I am not entirely certain if this is the case.
With this information in mind, it would be extremely helpful if anybody could provide input on the following: 1) indeed, the living stipend needs to be paid quarterly, 2) if the reason I owed alot of taxes is because of the discrepancy of tax bracket calculated from my hourly job which does not take into account the stipend income, 3) I should not have owed additional taxes due to the income types which is not accounted for by turbotax, 4) if I should adjust my taxes from my hourly job to not underpay again (see 2 above) using a fixed percentage, and 5) what that fixed percentage should be for fed, NY state, etc.
Thank you in advance for your thoughts and advice. I highly appreciate anyone's time and thoughts put forward in order to help.