Loaning
money to the corporation doesn't create income and paying it back doesn't
create an expense. So, the "in and out" don't hit your tax return unless
you're required to maintain a balance sheet (Schedule L).
The accounting entry is Debit Cash, Credit Shareholder Loan Payable. All on the balance sheet.
The
size of the loan matters because over $10,000 the Corp. is required to pay the
lender (you) interest at the Applicable Federal Rate (AFR). If you didn't actually pay the interest they call this
"imputed interest". This is an expense to the Corp. and income
to you.
If the interest is over $10 you are also required to file a 1099-INT
