Converting 401(k) into 403(b)

We have a client who currently sponsors a 401(k) plan but would like to convert it into a 403(b).  Is that something that can be done through a simple restatement of the Plan Document?  Or would we need to terminate the 401(k) and start a brand new 403(b)?

Thanks in advance!

You cannot convert or restate a 401(k) plan as a 403(b) plan.  Seriously re-consider keeping the 401(k) plan.  It is legally permitted to terminate the 401(k) plan and start up a new 403(b) plan from scratch.

That's what I was thinking.  We are just being introduced to the client, so I'm not entirely sure what the thinking is

Assuming the entity is eligible for a 403b plan, I'm not aware of any requirement to terminate the existing plan.  It could be frozen, w/o termination.