Does Buying a Put Option after Selling a Call Option at a Loss Trigger the Wash Sale Rule?

Generally, no. A call option and a put option on the same underlying security are typically not considered "substantially identical" because they represent opposite market positions.

Selling a call at a loss and immediately buying a put is usually not a wash sale, but the IRS could challenge the intent if the positions are part of a larger, aggressive tax-loss harvesting scheme.