Answer:
No, Jim is incorrectly applying the Statue of limitations and it would be wiser not to prepare his returns for 2016 through 2018.
Step-by-step explanation:
The IRS won't apply the Statue of Limitations in many cases, specially if a tax return wasn't filed, which is Jim's case. The IRS statue of limitations could be for up to 10 years to collect taxes weather the tax returns were filed correctly or not. Another important factor to consider is that no deadline applies to the IRS if they can prove that the taxpayer filed a false return, attempted to evade tax willfully or more importantly, failed to file a return. If you were to help Jim prepare his returns without filing for 2015, you could latter be implicated as an accomplice of Jim's fraudulent return.