IRS Notice regarding "Deferral for certain Sch H or SE Filers" from my 2020 return.

"there was a "Deferral for certain Schedule H or SE filers" claimed on Part II, Line f of Schedule 3 of the 1040. "

Not sure what "decrease in credit" means, but if you took this deferral it is time to pay.

Follow the instructions in the letter since it is a special case.

@frandan5709 

The self employment tax deferral was an optional benefit.  It is also a deferral rather than forgiveness, so those amounts will eventually need to be repaid. Half of the deferred amount is due on December 31, 2021, and the other half is due on December 31, 2022.

Check if you have a Schedule 3 line 12e which goes to 1040 line 31.

See this video on how to pay

How do I find out how much I owe in deferred taxes? 

Individuals can pay the deferred amount any time on or before the due date. They:

• Can make payments through the Electronic Federal Tax Payment System or by credit or debit card, money order or with a check.
• Should be separate payments from other tax payments to ensure they are applied to the deferred tax balance on the tax year 2020 Form 1040 since IRS systems won't recognize the payment for deferred tax if it is with other tax payments or paid with the current Form 1040.
• Should designate the payment as "deferred Social Security tax."

Individuals making deferred Social Security tax payments in EFTPS should select 1040 US Individual Income Tax Returns and deferred Social Security tax for the type of payment. They must apply the payment to the 2020 tax year where they deferred the payment. Taxpayers can visit EFTPS.gov for details.

These were the screens you should have seen in the 2020 program ...

If I had been asked CLEARLY if I wanted to take advantage of a deferral or just go ahead and pay, I would have chosen to pay.  It seems that Turbo Tax just automatically assumed I wanted the deferral. 

Sorry ... but if you read the screen shot you were  asked how much IF ANY you wanted  to defer ... it was your choice to make.