Ok... we (and probably you) are confused ... just because the same word standard is used they are not the same thing on a Sch C and a 1040.
If you file a Sch C with the 1040 you get to take all allowable business expenses on the Sch C (which includes taking the standard mileage or actual auto expenses deduction) AND use EITHER the standard or itemized deduction (Sch A) later on the return.
Now if you took the standard MILEAGE rate for your auto expenses on the Sch C and you want to change to the ACTUAL auto expenses then you can amend the return.
And/or if you believe your itemized deductions are better than the standard deduction then that is also a reason to amend the return.
