The U.S. Internal Revenue Service (IRS) acknowledged last week that it missed the April 8 cut-off for Windows XP support and will be paying Microsoft for an extra year of security patches. But the tax agency disputed an earlier estimate by Computerworld that put the cost of those patches in the millions, saying that it was paying Microsoft “less than $500,000″ for the after-retirement support. Microsoft terminated Windows XP support on Tuesday when it shipped the final public patches for the nearly-13-year-old operating system. Without patches for vulnerabilities discovered in the future, XP systems will be at risk from cyber criminals who hijack the machines and plant malware on them. During an IRS budget hearing on April 7 before the House Financial Services and General Government subcommittee, the chairman, Rep. Ander Crenshaw (R-Fla.) wondered why the agency had not wrapped up its Windows XP-to-Windows 7 move.