Am I responsible for a wrongful dismissal claim that was filed before I bought the business?

It depends on how you bought the business. In a share purchase, yes, generally — a wrongful dismissal claim against the corporation is a liability of that corporation, and since you now own it, the claim (and whatever it eventually costs to resolve) continues along with everything else you acquired, unless your purchase agreement specifically addresses it through an indemnity, holdback, or price adjustment tied to the outcome.

In an asset purchase, generally no — the claim is against the selling corporation as the employer at the time of the dismissal, and a properly structured asset deal should leave that liability with the seller rather than transferring it to you as a separate legal entity that wasn't the employer when the dismissal happened.

Either way, a pending wrongful dismissal claim discovered during due diligence deserves real attention: understand what's being claimed, get a sense of potential exposure, and make sure your agreement reflects who's actually responsible for it based on your deal structure, rather than leaving it as an assumption. A Treadstone business lawyer can help assess the claim and structure appropriate protections.