@avadventurespllc
from your post " Taxpayer TIN in the Return Header must not be the same as a TIN of a previously accepted electronic return for the return type and tax period indicated in the tax return. " says to me the rejection is because you are using a TIN/SSN asking for extension when a return with the same TIN has been accepted for processing.
What do you mean a business return using the same TIN. A business return cannot have the same TIN as the owner if it has a separate existence ) because a self-standing entity will be filed not on 1040.
You can see I am very confused as to what you have done -- please can you explain ?
At the same time ,and despite the rejection, you can still file your return as soon as you are able to -- an accepted extension really does not change anything as long as you file before Oct. 15th ( to avoid failure to file penalty ).
Will circle back once I hear from you.
