Maybe as an ATX customer you can get ProSystem fx as pay per return to prepare this corporation. Definitely look for a mentor. Extend if you have to to be able to be unrushed, as well as not rushing your mentor. Start with things you might have around, like TTB Deluxe or your old accounting book. You already understand the P&L and depreciation and lots of issues, as well as know the client and how he works. The biggy is the balance sheet. Read up on it in an old accounting book or Accounting for Dummies. Don't trust his QB to produce an accurate BS. Build it yourself by asking him questions and researching his ending bank balances, loans in and out, capital assets and corresponding depreciation, etc. Just go down the lines on the BS to see what applies to him. I think starting from scratch is the way to learn with a single shareholder corporation. The starting balance sheet will be all zeros. I actually think C-corporations are the easiest since they stand alone. Either they balance or they don't. If you're lucky, you client has treated it like a corp, like a separate entity, and there won't be undocumented back and forth with his personal accounts like you see with your small Schedule Cs and partnerships. Get his payroll documents. You may have to do or redo his bookkeeping, but you will really know the flow of his company if you do his bookkeeping too. Post here as you have questions. Keep us posted.