ASPPA says the reason is because of the delay in the release of the official forms and instructions. In its letter to the IRS, ASPPA pointed out that it is impossible for filers to submit the large number of filings that are due within the currently provided time frame without the official forms, instructions, and ability to file the Form 8955-SSA electronically through the Filing Information Returns Electronically (FIRE) system.
A revision of the due date for filing the 2009 and 2010 Form 8955-SSA would eliminate the need to file Form 5558 to extend the due date of such filings.
ASPPA suggested that the filing deadline for the Form 8955-SSA for any plan year beginning in 2009 and 2010 should be changed to no earlier than 180 days following the date the IRS releases the official form and instruction to the public and the FIRE system is available to support receipt of Form 8955-SSA filings. Thereafter, such 2009 and 2010 plan year filings should be due by the due date, with extensions, for filing the related plan’s 2010 Form 5500 series report.ASPPA’s letter is here.