If you want to change your filing status from single ($6,350 standard deduction) to Head of Household ($9,350 standard deduction), then you will need to amend your return.
If you're referring to the newly signed tax law, standard deductions do not increase until tax year 2018 (you will file that return in 2019).
You can not add the form/information to your original tax
return once it has been filed AND
accepted by the IRS. If it gets rejected, however, just log back in to
your tax return add the form and make any other necessary corrections.
If accepted, you will need to file an amended return (1040X)
to show the additional form/information. You should not try to amend your
return until the original return has been fully processed and you have received
your refund or your payment has cleared.
Amended returns do not “catch up” to your original return
and replace them; they are processed as two separate returns.
Amended returns have to be printed and filed by mail. It can take the IRS up to 12 weeks or longer
to process them. If you are due a
larger refund than on your original return, your amended return should only
show the difference and you will receive a separate check for it. If you owe money on your amended return, it will
show only the new amount owed, you will have to mail a check with the return.
Click here for the 1040X: https://ttlc.intuit.com/questions/1894381-how-to-amend-change-or-correct-a-return-you-already-filed
