Cash Balance Plan - Interest Rate Amendment

We have a Cash Balance Plan that has been adopted since 2020.  For 2024 they have elected to amend the guaranteed interest rate up to 6%.

My question is how does this impact 2020-2023.  When we are accruing balances going forward, are those years still credited at 5% annually and all new years credited at 6% annually?  Or should those years have accrued interest at 5%, but going forward they too get an interest rate of 6%?

Basically, does the 6% only impact new contributions or does it impact all contributions moving forward?

I hope that makes sense!

I would guess that unless the amendment specifies it, you start with your BOY balance 1/1/24 and start that at 6% along with new contributions, but you don't then retroactively increase the priors. Whether the prior benefits stay with a 5% ICR is going to be indicated in the amendment.