Form 5305 is not specifically related to any filing deadline. However, if you are referring to Form 5305-SEP (Simplified Employee Pension - Individual Retirement Accounts Contribution Agreement), the penalty for late filing can be up to $50 per late return or statement, as stated by the IRS. It's important to note that penalties may vary depending on the specific circumstances and the discretion of the IRS. It is recommended to consult a tax professional or refer to the official IRS guidelines for the most accurate and up-to-date information.