I am in the process of amending my 2019 return because we forgot to include my wife's self employment income which was about $2,000. i already received my refund for that

[Adam80]

year in the amount of $4,640. however when i got to the end of my amended return, (which i haven't submitted yet) it says im getting a refund of $4,084. why is that?

[Critter-3]

Look at the form 1040X …

Column A should have the figures from the original return, Column C the corrected figures and Column B the differences between the other 2 which needs an explanation on page 2 of the form 1040X.

If you completed it correctly you will see an entry on either line 16 OR 18:

On line 16 should be the amount you paid with your original return. 

On line 18 should be the amount of your original refund you received.

Then you will see your extra refund on line 22 OR  the new balance due you need to pay on line 20.

[fanfare]

If you add income, your tax will go up.

The additional amount you owe now is shown on line 20.

If you don't have an amount there, you filled out the 1040-X incorrectly.