Schedule SE-T error on federal review tells me to enter line 18,thought turbo tax does this on its own?

Line 18 isn't automatically filled out because it calls for you to make an estimation.  Only you have an idea of what the amount might be.  

See the instructions for Line 18 of Schedule SE in the IRS's 2020 Instructions for Schedule SE for guidance on what you need to enter.  The instructions are very vague, but also open-ended, allowing you to use any reasonable method:

Use any reasonable method to divide the net profit or (loss) you reported on line 3 between (a) January 1, 2020, through March 26, 2020, and (b) March 27, 2020, through December 31, 2020. A reasonable method will accurately reflect the time when income was earned or accrued and deductible expenses were paid or incurred, depending on your method of accounting. In most cases, a proportional division of the amount reported on line 3 based upon the number of days in each period will be considered reasonable.

John, that was very useful. I was about to submit the same question and then I saw what you had written. Thanks.

Well every the form has been filed and this is the first year its asking me this? Can someone from turbotax respond to this , it doesn’t ask for estimation it says from a march date toll december .. that form schedule c is in turbo tax and i thought should be figured out electronically like everything else.. what am i missing?

Is this something new ? And why?

Gladys, what John the Turbotax person said in his reply above is that TurboTax knows your Total income you entered, but it doesn't know how much of that income came between January - March 26th and which part of the income is from March 27th to December 31st. Only you can know that. So figure out how much of your full year tax was from March 27th to December 31st and enter it in line 18. 

John's explanation was actually very good

it depends.  The reason why it is asking you to enter an amount in line 18 is that because of COVID, the IRS is offering a break for the Self-Employment tax. So if your net profit was $48,000 for the year and if most of that was made before March 27, this will lessen the self-employment tax you would need to pay for the year. 

For a real life example, if you made $48,000 but $40,000 was made before 03/27, you would put $8000 in the that entry. This will prove to the IRS that you had a loss of income from 03/27-12/31. This is something that you will need to determine and decide what amount to record.

Awesome reply Dave. Thanks.

Thank you this explains it much better and i understand that it will be bcus of the covid new tax laws that’s why i was so confused 

In the case of a loss for 2020, the software seems to have a looping error.  In my case, I had a loss for 2020. When I enter a negative number for Sch SE Line 18, it says "Minimum Value is 0".  If I enter "0" or anything greater, the software says "Max deferral Line 18 is too large."  So there literally appears to be no value that the software will accept, and without fixing the problem, I can't e-file.  Any solutions out there?

Why doesn't the interview ask me to enter a value rather than surprising me with an error during the review?

I'm sorry to say that I don't have a solution for you because I am in the same boat.  I do look forward to hearing from someone about how to proceed.  Good luck to us both.

Try deleting the zero and just leaving it blank. That worked for me enough to e-file.  

What if most of the income was made during the period of 3/27 - 12/31 and the amount is larger than the amount on line 3?

Thank you dan92648.  Leaving the entry blank did the trick. 

DaveF1006, regarding SE-T line 18...the amount of income for the period of 03/27-12/31 is larger than the amount stated on line 3 and line 18 won't take the larger amount.  I'm not sure what to enter in line 18???  Do I enter the amount of line 3 on line 18??? 

Line 18 cannot be larger than the total net profit from Schedule C. If it was all earned after March 27, it would be the same. See 2020 Schedule SE.

To clear this error, leave the cell blank when prompted to defer self-employment tax.

Run the review again.

If this does not clear the error, try:

1. Delete the Sch SE that applies--(Sch SE-T is for Taxpayer, Sch SE-S for Spouse)--by following these steps:
   1. From the left menu, select Tax Tools.
   2. Select Tools.
   3. Scroll to Delete a Form.
   4. Scroll to Sch SE-T and/or Sch SE-S and select Delete.
2. Return to the self-employment income & expenses interview in the Income & Expenses section and select Edit/Add.
   1. Select Edit for your business.
   2. Scroll down to Done so that the Sch SE is recalculated. 
   3. Finish any other questions in the self-employment interview and click Continue.
3. Review the return again.

If this does not clear the error, then click this link for more information: 

Workaround for Sch SE-T error for deferring Self-Employment Taxes.

@BCholt12

It worked for me to leave it blank, but I had to leave it blank in both the box above the form and the form itself had to be blank, no "0.".  Good luck!