Sorry but this is a user data entry because you failed to read the screen that told you what had already been entered. If you made a duplicate entry then you have only yourself to blame.
If you had entered the Sch A deduction first then back tracked to the Business tab to enter the home office expenses then the same cross reference would have happened there as well. The program computes how much is deductible on the Sch C & the Sch A ... you do not need to do this yourself. If you do choose to do the proration yourself then again you should never enter more than 100% of the amount and at no time should you enter an income or expense amount in full twice.
