So if I don't pay my taxes...then what??

[nevadaJACK]

All these tax posts made me want to learn more about just what the consequences of non-payment are (since anyone considering not paying them would probably at the least want to weigh the risks versus the benefits).

So hypothetical:

JACK has a full-time job, but enjoys high limit online poker in his spare time. He makes a poker profit of $80,000 in 2005, but doesn't declare any of it on his tax return.

He gets audited by the IRS who discovers this and tells him that he filed an erroneous tax return by leaving out his poker winnings. It turns out that Jack should have paid approx $30,000 in income tax on his poker profits.

- What happens then?
- What is the penalty?
- Does JACK then have any kind of black mark on either his credit record or IRS internal records?
- Is his act criminal, and will he have a criminal record?
- Does it matter whether Jack knew that he was withholding his poker winnings (presumably fraudulent), versus whether he has a reasonable (even if ultimately rejected by the IRS) argument as to why he left them off (let's say for the sake of argument that he was able to make such a showing, even if extremely unlikely -- I only add this twist because from some of the IRS language I read, the penalties are somewhat less harsh if the filer had a reasonable basis for his actions).