I paid estimated taxes as a grad student, as my university wouldn't do withholding on fellowships. I sent in a 1040ES every quarter.
In many cases taxpayers get one "freebie" year of underestimating their withholding before penalties kick in. According to the IRS:
"Generally, most taxpayers will avoid this penalty if they owe less than $1,000 in tax after subtracting their withholdings and credits, or if they paid at least 90% of the tax for the current year, or 100% of the tax shown on the return for the prior year, whichever is smaller."
So, if your withholdings for this year are at least as much as you owed in taxes last year, you are in the clear. Also, it looks like the penalty is in the neighborhood of 2.5%. So on a $1400 underpayment you are looking at less than $50 even if you do get penalized.
OK, that would be the situation I am in. Withholding for this year will definitely be larger than last year.
Pry,
I made an additional $5000 this year and think the underpayment will exceed $1000. The tax bill last year was about $6000.