First time owing Federal. I just want to make sure I don't screw something up, any help would be amazing.

I recently got a new job making quite a bit more than I have before. And for the past 20 years, filing 0 dependents and married filing jointly has resulted in a decent return.

This year however, I owe $5,200. I know it is 100% my fault for not looking more closely at my withholdings. But this is the first time I've owed on state **or** federal.

I've read many threads and articles about the correct way to file and pay, but I just want to be absolutely sure I'm not gonna screw myself further than I already have.

So I have three questions:

1. How do I verify that the amount I'm paying is the exact amount that I actually owe? Should I consider the amount that is shown on freetaxusa to be accurate? I just don't want to be $100 off for some reason and then have to pay another penalty on top of everything.

2. I will need to pay this in 4 installments. The IRS site seems to have a labyrinth of rules and different qualifiers for different payment plans. Can I actually do this? If so, does anyone have a link to the exact place?

3. Do I have to send the forms along with the payment? If so, can I set up and payments online and send the 1040 in one go?

Again, I know this exact thing has probably been answered many times, but I'm already having panic attacks about this, so I just need to know that I am correcting my mistake the right way.