How can I enter numbers in to resolve the"Check This Entry" Sch SE-S: Max deferral line 18 "must be entered" error in review? It won't let me enter a number and continue.

This is a question because of initially qualifying to defer a portion of your self-employment tax, before all the details were entered into the return. Once a refund was established, the deferral was no longer an option.

If you return to the section directly, you may not see the screens necessary to adjust this since you no longer qualify for the option. 

The easiest and fastest solution is to enter nothing--leave the response blank.

If you cannot leave the response blank, then first make sure the program is up to date by following these steps:

Step 1:

• TurboTax Online: Close out of the program completely and close the browser. Re-open using an incognito Chrome browser on a PC, not a Chromebook or iPad.
• TurboTax CD/Download: Check for updates--depending on your version, this is found either under the menu item Online or Help.

Step 2:

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 box cannot be left blank after updates and after deleting Sch SE, and you are still experiencing unexpected results, then there is one more process to try: temporarily trigger a balance due by adding income long enough to decline the SE tax deferral option, then remove the extra income.

To do this in TurboTax, follow these steps:

Enter a temporary amount as income in the self-employment section that will result in you not having a refund.

1. From the left menu, select Federal.
2. From the Income & Expenses, scroll to Self-employment income & expenses and Edit/Add.
3. At Your 2020 work summary, select Edit.
4. Under INCOME, select Add income for this work.
5. Add Other self-employed income, includes 1099-K, cash, and checks and Continue.
6. At Type of income, enter Temp income to remove deferral and enter a large amount, such as $100,000 and Continue.

Decline to defer any self-employment tax.

1. From the left menu, click on Federal.
2. Click the second tab from the left, Deductions & Credits.
3. Scroll down to Tax Relief related to Covid-19 and Revisit.
4. Select Self-employment tax deferral and select Revisit.
5. Answer Yes at the next screen to get back to Let's start by getting your eligible income
   1. Enter 280/366ths of your income to reflect the income from March 27-December 31, 2021. 
      • This amount should be calculated and entered without the false added income, and will post to Line 18 of Sch SE
   1. ​​​​​​​Select Continue.
   1. At Tell us how much you'd like to defer, 
      • Enter 0.

​​​​​​​Remove the temporary income.

1. From the left menu, select Federal.
2. From the Income & Expenses, scroll to Self-employment income & expenses and Edit/Add.
3. At Your 2020 work summary, select Edit.
4. Under INCOME, select the Trash can icon next to Temp income to remove deferral and Continue.

For more details, see TurboTax Expert @DawnC's answer here, about 2/3 down the page: Resolve Sch SE-T Max Deferral Line 18 must be entered.