I received an IRS letter requesting additional documentation for my 2017 Sch C - is there a way to access the data that I entered that led to the sum totals?

[Anonymous]

open the tax return for 2017 and go to schedule C.  we can not see the return so if you entered details for various lines you  should be able to view them.  if you only entered totals for the various lines from the data you had, then you'll have to find the original data and figure out what line you used.  If you no longer have that data, you are at the mercy of the IRS unless you can obtain duplicates from the source.  make sure to respond by deadline, contact IRS if you need additional time.  failure and the IRS will probably deny the deductions they're asking you about.     that would leave you with not very good options.   pay what the IRS says you owe or hire a pro to go to court for you.   A pro MIGHT be able to get a settlement for less than the full amount owing.  

[Critter]

If you want to see all your entries and the PDF of the return with all the worksheets is not enough then you can download the amendment program to open the return and review the entry screens.