Cross tested 3% safe harbor plan with last day rule

[alwaysaquestion]

I have a plan that is a 3% safe harbor and a cross tested profit sharing (each person is in their own group).  There is a last day and 1000 hours requirement for the profit-sharing allocation.  This is a 12/31/2023 plan year end.  Can I do an amendment in 2024 to take out the last day and 1,000 hours requirement for the 12/31/2023 plan year by the end of 12/31/2024?

[CuseFan]

I think under the SECURE 2.0 benefit increase amendment, if that even applies in this instance, that you'd have to amend by tax return due date, including extensions - or, if you need to take that out to be able to allocate gateway and pass testing then you could do an 11(g) amendment by 10/15. Either way, I don't think you can go out to 12/31/2024. If the plan was properly designed and drafted, you should have overriding gateway allocation requirements (if that's your issue, and I think most pre-approved documents now have that) or those allocation conditions should have been removed as incompatible.