The US government agency notorious for coming down hard on Americans that miss tax deadlines just admitted to missing a simple deadline it knew was coming since 2008.

The Internal Revenue Service (IRS) acknowledged it missed the April 8 deadline for migrating from the Windows XP to Windows 7 operating system. As a result, the IRS will be paying Microsoft, Inc. millions of dollars in taxpayer money for one extra year of security patches.

Microsoft ended its support for its popular 13-year-old Windows XP operating system last April 8 when it shipped the final public patches for XP. Without these patches that fix software vulnerabilities, IRS computers running on XP will be at risk from cyber criminals that hack these computers or infect them with malware that steals passwords and other vital taxpayer information.

The IRS said it has some 110,000 Windows-powered desktops and notebooks. Of this total, 52,000 or 47 percent have been upgraded to Windows 7. The remaining 53 percent or 58,000 computers continue to run on the now retired XP.

Experts estimate the IRS will wind up paying Microsoft $11.6 million for one year of what is called "Custom Support" for its Windows XP computers. The IRS will spend another $18.4 million to buy new PCs to replace the oldest ones running XP.

House Financial Services and General Government subcommittee chairman Rep. Ander Crenshaw (R-Fla.) asked why the IRS failed to meet the deadline during a recent IRS budget hearing.

"Now we find out that you've been struggling to come up with $30 million to finish migrating to Windows 7, even though Microsoft announced in 2008 that it would stop supporting Windows XP past 2014," Crenshaw said at the hearing.

IRS commissioner John Koskinen, however, defended the unfinished migration. He noted that the IRS had $300 million worth of IT improvements on hold because of budget issues. One of those was the XP-to-7 migration.

"You're exactly right," Koskinen said about Crenshaw's argument that people had fair warning of XP's retirement. "It's been some time where people knew Windows XP was going to disappear."