Can anyone help me understand what is the amount shown in line 31 of tax return document

Look at Schedule 3 Lines 9 thru 12 and 14.  There will be an amount shown on one or more of those lines.  Which line or lines have an amount?

You can view your Form 1040 plus Schedules 1, 2 and 3 at any time using the online editions. Click on Tax Tools on the left side of the online program screen. Click on Tools. Click on View Tax Summary. Click on Preview my 1040 on the left side of the screen.

Yes, this amount is Other payments, which Includes:

• Premium Tax Credit
• Estimated payments and payments made with extension
• Excess social security and tier 1 RRTA tax withheld
• Credit for federal tax on fuels
• Other, less common tax credits

If you still aren't sure where this number came from, check Schedule 3, Part II.