Is an HOA estoppel fee paid by the seller at closing an includable seller expense?

There seem to be differing opinions on the forum over the years so I'm hoping some CPA/tax experts will chime in and put this question to rest...

Upon selling a home is an HOA estoppel fee that is part of the seller's closing costs an includable seller expense for the purpose of reducing a gain on the sale?

(In this scenario I don't believe it matters if the home is a primary residence, a second home or an investment property, but if it does then please clarify as well)