The exception under which a court holds an owner personally liable for a company's debts, despite the limited liability the company normally provides.
Forming a corporation or an LLC creates a separate legal person, and that separateness is what limits an owner's exposure to what they put in. Piercing the veil is the exception: a court sets that separateness aside and reaches the owner personally. It is applied sparingly, and it is a remedy a court imposes rather than a claim that stands on its own.
Courts describing the doctrine tend to look at two things together. The first is whether the company was genuinely operated as a separate entity - its own bank accounts and records, observed formalities, adequate funding for the business it undertook, and no routine mixing of company and personal money. The second is whether respecting the separation in this particular case would work an injustice, most obviously where the entity was used to defeat a creditor or a legal obligation.
What follows from that is the practical point: the protection is not conferred once at formation and kept forever. It is maintained by how the business is actually run, and the fact patterns that produce piercing are usually mundane housekeeping failures rather than fraud.
The valuable conversation is the preventive one, and it is short: separate accounts, a written record of decisions, contracts signed in the company's name, and no informal transfers between owner and entity. If a creditor is already arguing alter ego, the analysis is fact-heavy and turns on records that either exist or do not - which is why the answer is usually determined years before the dispute.
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