Not sure which plan you are referring to. If this is for IRA contribution, you can still contribute to an IRA up until April.
You may be able to deduct some or all of your contributions to a traditional IRA and lower the amount of taxes that you owe on your 2022 return.
For more information please check:
IRA Contribution Limits
IRA Deduction Limits
To that section in TurboTax: Where do I enter my traditional or Roth IRA contributions?