Because it's supposed to. When you file an amended return, you are "in fact" changing figures on the originally filed 1040. The 1040 X shows what the old figure was before the change, and what the new figure is after the change.
The following is provided for others that may see this thread.
Already E-Filed and
Need To Change
If you have already E-filed your tax return and need to make
a change for any reason, then you have no choice but to wait until the IRS
processes your E-filed return. If the IRS rejects your E-filed return, then you
can just make the necessary changes and resubmit it.
If the IRS accepts your E-filed return, then you must WAIT
until the IRS has processed your return. If you have a refund due your return
is not processed until you have received your refund. If you owe taxes, your
refund is not processed until you have paid those taxes and your payment has
cleared your financial institution. Once processing is complete, you will need
to file an amended return. You can not e-file an amended return. The IRS says
you can’t. You have to print it, sign it (both the 1040 and 1040X) and
physically mail it to the IRS.
If your E-Filed return is pending, and you change anything
on your copy of your return, then you are guaranteed
to have major issues with correcting
or amending it later. So for your own sanity, do not touch anything until it’s
time, as clarified above.
An amended return must be printed, signed and mailed. The
IRS says so.
If my return is accepted, why do I
have to wait for my refund before I can amend it?
Just because the IRS has accepted your return, does not mean
that they agree with it. Sometimes, the IRS will “catch” your error (or some
other error you don’t know about) and go ahead and correct it for you. You’ll
know that when your refund is not what you expected. So you have to wait for the refund. If that happens to you, then you will receive
a letter 3-4 weeks after you receive your refund, explaining what was changed,
why it was changed, and with instructions on what actions to take if your
dispute the change. If
you receive such a letter, post in this forum with the details (without including personal information)
and we'll try to help you get your copy of the return in agreement with the IRS
changes, so you won't have issues importing next year.
