1040-X basic, (hopefully) ,question

[Sausalito789]

I'm confused.

1040 sent, let's say 500 USD refund expected. Late 1099 comes in need to send 1040-X with refund now recalculated at let's say 450 USD.

So, am I expecting:

a - A refund for $500 and then I send them a check for $50?

b. A refund for $450 straight out the gate and that's it?

I'm thinking the way the 1040-X form calculates the numbers the IRS are expecting a payment from me that covers the 'refund' excess?

I also see references to 'waiting for the IRS to accept your 1040 before sending in the 1040-X'. How is that verified?.....USPS return of the certified mail receipt postcard.....or...wheres my refund....or what?

Thanks

[Sausalito789]

OK I checked the 'Wheres my refund' and the refund has been approved and processed, so it looks like I need to send in a refund to the IRS for the over payment from them. So can I use their credit card system and make the payment and then send in the 1040-X via mail with the 1099 and the credit card receipt attached?

Thanks