When a SIMPLE plan is in place, is it possible to put a 412(i) db plan in during the same year --- does it matter whether or not contributions have already been made to the SIMPLE plan this year?

Also, can the SIMPLE plan be immediately terminated and another plan started, or, is there mandatory waiting period - or does it depend on whether contributions have already been made to the plan this year?

If a DB is established (and benefitts accure) during any period in which there is a SIMPLE plan; all contributions to the SIMPLE plan become excess contributions.