Interest rates; underpayments and overpayments. The rates for interest determined under section 6621 of the Code for the calender quarter beginning April 1, 2010, will be 4 percent for overpayments (3 percent in the case of a corporation), 4 percent for underpayments, and 6 percent for large corporate underpayments. The rate of interest paid on the portion of a corporate overpayment exceeding $10,000 will be 1.5 percent.

Fringe benefits aircraft valuation formula. The Standard Industry Fare Level (SIFL) cents-per-mile rates and terminal charge in effect for the first half of 2010 are set forth for purposes of determining the value of noncommercial flights on employer-provided aircraft under section 1.61-21(g) of the regulations.

Substitute tax forms and schedules. Requirements are set forth for privately designed and printed federal tax forms and conditions under which the Service will accept computer prepared, and computer-generated tax forms and schedules. Rev. Proc. 2009-17 superseded.