When you mark the S-corp return as final, it will automatically blank out the "end of year balances" on the balance sheet. You can enter your beginning balances on the tax return but only use 01/01/2017 where it asks for any dates. If you enter dates prior to 2017, it could create problems. The exception is the assets. You can enter the old purchase date and the prior depreciation. You may not have to enter the balance sheet at all, see below:
If your receipts for 2017 were less than $250,000 and the total assets on 12/31/17 were less than $250,000, you don't even have to complete the balance sheet.
On page 2 of the 1120-S (Schedule B, Other information) question 10 is:
10 Does the corporation satisfy both of the following conditions?
a The corporation’s total receipts (see instructions) for the tax year were less than $250,000 . . . . . . . . . .
b The corporation’s total assets at the end of the tax year were less than $250,000 . . . . . . . . . . . .
If you check “Yes,” the corporation is not required to complete Schedules L and M-1.
