IRS audits only a small fraction of the millions of tax returns that it receives each year
. If we take the average of the returns that it audits in a year then it is just 2% of the total received. IRS do not audit a tax return until there is some kind of key indicator like a deduction that involves documentation, a high level of deductions against income earned etc. If you receive some kind of intimation stating that you are going to be audited then you should contact your accountant or IRS tax attorney immediately.
Its not that anyone can send a request for audit to IRS. Even if your return falls in either of the categories, your application may still be ignored. There are many other eligibility criteria also including:-
Self employed,
a very high salary
Large list of itemized deductions etc.
If you are selected for IRS tax audit then it will be not that an IRS representative will come to verify your financial documents. Majority of the work will be done by the mail. Also it may happen that the IRS will not audit your entire tax but a portion of it instead.
IRS will help you to outline the portion of tax or tax returns which is under dispute. When you get enrolled for IRS audit, there will be several rights involved. You have full authority to exercise these rights. If you want to avoid tax audit by IRS then the best way is to prepare and file an honest tax return every year.