IRS information returns can be due January 31th, March 15th, April 15th, May 15th and later (with extensions).
For the Club, the main information return is Form 990-T. From the IRS 2014 Form 990-T instructions:
“When To File
An employees’ trust defined in section
401(a), an IRA (including SEPs and
SIMPLEs), a Roth IRA, a Coverdell ESA,
or an Archer MSA must file Form 990-T by
the 15th day of the 4th month after the end
of its tax year. All other organizations must
file Form 990-T by the 15th day of the 5th
month after the end of their tax years. If
the regular due date falls on a Saturday,
Sunday, or legal holiday, file no later than
the next business day.”
In other words, May 15th.