The deadline to contribute to a SEP IRA (Simplified Employee Pension Individual Retirement Account) for a given tax year is typically the tax return filing deadline, including extensions. For the tax year 2022, the deadline to file taxes is April 15, 2023. However, it's important to note that tax deadlines can vary, and it's advisable to consult with a tax professional or the Internal Revenue Service (IRS) for the most accurate and up-to-date information.