1. This is not the type of thing to deal with on April 4.

2. You can file an extension showing he owes $XXXXX. Will he pay?

3. I hope the wife has been filing MFS returns all these years.

4. If you do take this on after April 15:

 a) You get a bucket of money upfront. When it's used up, you ask for more.

b) He hires a bookkeeper to construct/reconstruct books.

c) Plan on 3 years back taxes to get him in good stead.

5. Has IRS come calling? Have employees filed complaints, workman's comp claims? Does he have a valid business license? Has the state come calling?

Think hard before accepting. It's OK to say no. He probably should get a lawyer involved.

It's also OK to say I'll take a look for $XXX, upfront, and then let you know.