Advantage to signing new CB plan by 12/31 over retroactively signing by tax deadline?

Is there a particular advantage to signing a new Cash Balance Plan for the current plan year by end of the plan year, typically 12/31. 

Or is it just as well to wait until prior to the tax filing deadline of the next year and signing retroactively?

Depends on the circumstances. I don't think you want someone signing a plan on 4/14 expecting to fund a trust (that can't be set up earlier) on 4/15 so they can file on time. The advantage is for clients who don't want to extend their returns (and for those doing the work, fitting these new plans into their busy Q1 schedules). Also, some clients may want to begin funding sooner rather than later given market conditions at the time. And what's your guard against doing all the work up front so can accommodate, including the valuation, only to get hit with a late change of mind/chickening out and stiffing you on payment for work done?

Personally, the earlier a plan gets implemented the more time we provide our actuarial teams to do their work and I do not like to commit staff to aggressive unrealistic timing - been on the other side of that, it's unfair and bad for morale, IMHO.

Isn't one advantage signing after 12/31 not filing 5500 form? Actuarial certifications still need to be done

For example (extreme one):

S-corp (with employees) decides to start one on 9/14, signs and funds on 9/15. If wanted to file 5500 form, has to file on 9/15 (special extension) as no 5558 to extend to 10/15. Of course, it is assumed that s-corp tax filing is on extension.

Full disclosure, not a fan of above but happened once or twice😁

CuseFan has made good points. But more and more I think and encourage, the clients should start the plans after year end as the census data would be final and available and also allow a better design than making one up during the year as census changes all the time.

Just saying it.

I have found it most practical to create the document closer to the time the client is ready to fund.  I can't tell you how many plans were created in December when the client had tons of money, only to find out later when it was time to fund in September that circumstances had changed, and they did not have the needed funds.

1 minute ago, Jakyasar said:

Isn't one advantage signing after 12/31 not filing 5500 form? Actuarial certifications still need to be done.

Can it be created on 12/31 such that no accrual occurs until the next year?