How would you know if you had paid 100% of the taxes due unless you had done a tax return? If you had done a tax return, why wouldn’t you want to file it?
“What if you fail to file?
The IRS may file what is known as a substitute return for you. However, as you well know, the IRS will not be looking to save you any money. In fact, a substitute return will not include any of the standard deductions your accountant would typically include in your return. Case in point, a substitute return only allows one exemption: single or married filing separate, so you end up with higher tax liability than if you would have just filed.”
There are also statute of limitation provisions that are activated by filing….see linked article