Important Due Dates   Form 5500 and applicable schedule must be post marked by the last day of the 7th month following the end of the plan year.  An extension of 2 1/2 months may be filed, if necessary.   Deferral Deposits should be deposited as soon as they are separated from payroll .  To expedite this process, electronic transfers should be utilized on the day payroll is processed.   Profit Sharing Contributions are due by the business tax return due date.  In order for your contribution to be deductible, it must be deposited by the due date of your business return, including any extension.   Defined Benefit contributions  are due 8 1/2 months after Plan Year End.