Reasons not to ignore IRS notices

The IRS can pull money out of your bank account – notices are usually time sensitive, if you do not respond in time you will learn a tough lesson when your rent check bounces because the IRS drafted every penny out of your bank account.
They IRS may be filing a return for you – sound like they are doing you a favor? Probably not. Often in this case they simply file a return based on your income, without regard to any tax deductions. The result is an exaggerated balance due to be remedied by promptly filing a complete tax return.
Interest and penalties add up quick – If you are new to owing the IRS, you will be shocked to watch your balance grow rapidly due to interest and penalties. It is similar to a super high interest rate credit card, you are wise to pay off as much tax as you can immediately.