T/P is receiving refund for Tax Year 2019 and applying portion to 1st Qtr 2020.

Q1.  Is it really necessary to file extension, since no payment is due and failure to file penalty applies           to balance due only?

Q2.  Since T/P for whatever reason unable to sign 8879 and pay tax prep fee, once they do, then will 

         file return.  Once IRS receives and accepts return, when will the IRS apply portion of the                 

         refund to 1st Qtr 2020.....date they receive it correct or as of 7.15.20? 

Since T/P is filing late, the only issue I see is 1st Qtr 2020 Est Payment will be late, however if 2020 results in refund and they paid 100% of 2019 tax then there should be no underpayment penalties.

Correct?