Similar to its predecessor, the Form 8955-SSA is due by the last day of the seventh month following the last day of the Plan Year (plus extensions if applicable). An extension can be filed using the Form 5558, which is the same form used to extend the Form 5500.
There are special instructions for the 2009 and 2010 Plan Year filings. The due date for the 2009 and 2010 forms are the later of the due date for the 2010 form or January 17, 2012.
In addition, plan administrators may use a separate 2009 Form 8955-SSA to report information for the 2010 Plan Year or combine the information for the 2009 and 2010 Plan Years on a single 2009 Form 8955-SSA.
Instructions for the form can be found at: http://www.irs.gov/pub/irs-pdf/i8955ssa.pdf
The form itself can be found at: http://www.irs.gov/pub/irs-pdf/f8955ssa.pdf