October 15, 2025 (11:59 PM ET). Betterment’s 2024 SEP contribution deadline.

If you filed an extension and wish to contribute to your 2024 SEP IRA by the October 15, 2025 tax filing deadline, you must initiate your deposit through Betterment by 11:59 PM ET on October 15, 2025, to ensure that your contribution completes by the deadline.