Sorry for late response.  Just got back in town.

So... First notice was dated June 7th with full payment due date of June 28th.  And, he rec'd a demand to levy shortly after (July 2nd).  His total SE  $10,945, and deferred $3030.   it clearly stated on the 1040, total deferred amount $3030 and 1/2 $1,515 to pay by 12/31/21 and final 1/2 $1,515 by 12/31/22.  

I tried to call IRS numerous times but unable to connect with anyone.  I recommended my client to just pay it to avoid the additional hassle.