I did not receive the stimulus payment last year as my spouse has an ITIN. I know that to receive the recovery rebate this year on a joint return both me and my spouse need a valid SSN. So I am contemplating filing as 'married filing separately' to get my share of the recovery rebate ($600) and then correcting to 'married filing joint' using a 1040X to get the right refund. This is perfectly legal as it addressed on the IRS website. So as I run the scenarios this is what happens:

When I file the 1040 as married filing separately, I fall into a higher tax bracket ( quite naturally ) and I owe the IRS $300. Now by virtue of the recovery rebate credit I get a refund of $300. This refund is SOLELY due to the $600 RRC ( 600 - 300).

Now when I correct the 1040 using the 1040X and when filing the 1040X as married filing jointly, I automatically fall into a lower tax bracket and have a higher refund. For the sake of this example let us assume the refund is 3000$ (This amount is exactly the same amount as the amount I would have gotten as a refund if I had filed the 1040 as married filing jointly in the first place) As I go through the steps of filling the 1040X the form wants me to subtract the amount I got refunded in the 1040 from the amount due ( 3000 - 300 = 2700 ). So my refund on the 1040X reduces to 2700 for a total of $3000 ( $300 on the 1040 and $2700 on the 1040X)

I think this is wrong. The refund that I had gotten in the 1040 when filed married filing separately was due to the RRC and should not be something I should pay back. So instead of getting a total of 3000 I think I should get 3300.

Is my line of thought correct?

$3,300 is the correct amount, because you get the $300 you paid in BACK, but do NOT pay back the $600 RRC.