<prompt> Human: I started freelancing back in July 15 and have since made roughly 8,000. However, I didnt know I had to pay quarterly estimated taxes. Since this is my first year being self employed, is there a way that I can pay back my estimated taxes now its not estimated, because I know exactly what I made and my income tax all in one shot? I just want to get my taxes caught up and not get buried with penalties.  <response>: Yes you can pay your taxes now that you know what they really will be. Theres a chance you have an underpayment penalty, but it really depends on whether you had any total tax in 2014, and it depends on whether youve had other W-2 job withholding during 2015, so your post doesnt have enough information to say.What was your total W-2 income in 2015? And total withholding from such job?What was total freelancing income? Any business expenses you will be deducting?Youll use Schedule C-EZ or C to find your business profit and put it on 1040 line 12. Then youll use that profit also on Schedule SE to find your social security and Medicare taxes, for 1040 line 57. SE tax soc sec Medicare Sched C profit 0.9235 0.153You get to deduct half of that line 57 amount as a deduction on 1040 line 27.---Once you determine what your total tax is income tax line 44 SE tax line 57, youll be able to figure out whether you owe any underpayment penalty. Note: If you owe less than 1000 in taxes, no underpayment penalty.Form 2210 short method is what youd use. This is where youll need to know 2014 total tax amount, and 2015 W-2 withholding amount. The required annual payment is computed, and it might be the lesser of 100 of 2014 total tax; 90 of 2015 total taxFrom that, youd subtract any W-2 job withholding you had. Finally, you take the result and multiply by 2.01 to get the underpayment penalty, if any. That would go on 1040 line 79 and be included within your 1040 line 78 result. There is a more complicated method on Form 2210 called annualized income method you could use if you want to be more precise and explain that all the SE income was actually earned in the latter half of the year.That penalty amount may not be too significant, since your SE income is 8K. And if you had no other income other than that, you would have no income tax if youre not claimed as a dependent, and only a very small amount of income tax if you can be claimed as a dependent.Indeed, if the only tax you will be paying ends up being a small income tax and your SE tax, it might amount to less than 1000 if you have deducted some business expenses, and thered be no underpayment penalty at all.Not knowing if you have W-2 job income and withholding prevents me from saying anything more specific. 