Let's take a look at the arsenal of weapons the IRS can use to get a felony conviction for someone lying to an IRS employee and/or delivering false documents. The Internal Revenue Code (IRC) has two types of punishment for tax-related perjury violations: one is a misdemeanor; the other is a felony.
26 USC Section 7207
(misdemeanor)
Anyone who willfully delivers or discloses to the [IRS] any list, statement or other document, known by him to be fraudulent or to be false as to any material matter, shall be fined not more than $1,000, or imprisoned not more than 1 year, or both.
26 USC Section 7206(1)
(felony)
Anyone who willfully makes and subscribes any return, statement, or other document, which contains or is verified by a written declaration that it is made under the penalties of perjury, and which he does not believe to be true and correct as to every material matter shall... be guilty of a felony and, upon conviction thereof, shall be fined not more than $5,000, or imprisoned not more than 3 years, or both, together with the costs of prosecution.
18 USC Section 1621 (felony)
The so-called tax perjury statute 7206(1) and the general perjury statute 1621 are very serious felonies, but as you have noted, the above statutes require the taxpayer to perform particular overt acts. The tax perjury statute requires the taxpayer to submit a document (such as a tax return, financial statement, or affidavit) signed under the penalties of perjury.