I filed an extension to my 2020 tax return and submitted an estimated payment of $5,000. After filing electronically, I received a few months later a direct deposit refund but it was exactly $5,000 less than expected (line 38a____ of Form 1040-SR (2020). [ I know I shouldn't have sent so much $$ but wanted to be safe]. This was more than 5 months ago. I received no follow-on letter of explanation. How or to whom should I inquire at IRS to get my full refund? Thanks, Tom
