What's the protocol for estimated taxes at this point?=====>>as you can see, Whether or not your fellowship stipend is taxable depends on its use; only for educational purposes, are not taxable under IRS rule.
as a recipient of stipend , you need to make quarterly estimated tax payments to the IRS and your state revenue dept( If any part of your scholarship or fellowship grant is taxable)..However, the amount of some stipends may fall below the amount required to pay estimated taxes.. A scholarship /fellowship is tax free ONLY IF #1;you are a candidate for a degree at an eligible institution , and #2;you use the scholarship or fellowship to pay "qualified expenses" such as tuition and fees required to enroll and course-related expenses such as books, supplies or etc.since you're a graduate student, I'll presume that the condition #1 and #2 are satisfied.Anyway, aslongas you need to make quarterly estimated taxes on your fellowship , (The first estimated tax payment for the year 2015 is due by April 15, 2015)you need to pay at least 90% of the tax for the current year 2015(if you are able to estimate the amount in 2015), or 100% of the tax shown on the return for the prior year. For example, say your tax liability was $1.2K in 2014, then you need to pay$300 each quarter(april/june/sep/jan fo 2016); So, when you make your quarterly payment on April 15, you are paying on the income you had from January 1 to March 31 of that year
I would really rather not pay 90% of my 2014 taxes just to be safe, as I'm not getting paid anymore and need the money.====>>>>>I guess so.
Usually for the first year of estimated taxes, the government gives the individual a grace period where estimated taxes do not have to be paid quarterly.====>>It depends; If you pay your income tax in full by January 31st, you can skip the final estimated tax payment.
Does my leave of absence reset the situation back to my "first year" of estimated taxes?====>>as mentioned above; the safest way is to
Pay 100% of the tax shown on the return for the prior year. I’d do that if I were in your shoes.however,it is up to you.
Should I just pay depending how much I earn each quarter?========>>>Not really;it depends on your estimated annual income in 2015 or tax liability that you paid in 2014 as said.