What's the best course of action for an S-Corp formed in 2019, never filed the S-Corp tax docs in the 2019 tax year (bc no activity), and wants to terminate for 2020?

It depends. 

 

When you say you formed the S-Corp in 2019, clarify if you applied for an EIN from the IRS for the S-Corp or an LLC or not? 

 

If you only applied to your state for authority to operate, then and can notify the state to terminate. 

 

If you applied for an EIN for the entity in 2019, you should file a 2019 tax return (zero activity) and mark it the final return. 

 

You may receive a letter for late filing of the return and you can request a First Time Abatement of Penalty for late filing due to organizing and then the business never really started. 

 

You will have to apply to the state in either case to terminate the S-Corp.