Dealing with IRS problems is a stressful and scary ordeal if you fear that you may have done something wrong, either on purpose or completely by accident. The first thing to understand is that the IRS is generally willing to work with individuals who are willing to work with them. You can learn about some things that can get you in trouble here, as well as the best ways to try to work through those issues.
It's never a good thing to not pay your taxes. As soon as you realize that you aren't going to be able to pay them, you should contact the IRS. They are generally good about putting you on a payment program that allows you to pay on them over time, according to a set schedule. However, once you have agreed to this payment schedule, it's very important for you to stick to it. If you have to miss a payment, keep in contact with them and let them know what's going on. If you don't stay in contact with them then you may find yourself stricken with hefty fines and you'll see they won't be as lenient with you in the future.
Neglecting to file your taxes altogether is actually a lot worse than filing and then not paying what you owe. Once you realize you haven't filed, you'll want to make sure you do so immediately. The IRS is known for usually not punishing people who eventually file their taxes BEFORE the IRS notices and gets in contact with them.
Tax return audits
Just about everyone who files taxes will have it in the back of their mind at some point what would happen if they end up being audited. Audits are no fun because they require you to dig up a lot of proof, much of which you may not have a clue how you are going to find it. The good news is, unless you have done something that waves a red flag in the system, the chances are that you will never be audited at any point in your lifetime. If you are that concerned about an audit, then you may want to always have your taxes done by a tax professional you trust, so you know there won't be accidental mistakes made that can happen when you attempt to do them yourself.
Contact from the IRS
If you do receive any type of letter from the IRS that concerns you, then you should seek help from someone experienced to help you. Not only can this take some of the worry off you, but it also lets you know that things are being dealt with in the proper manner.