How long to I have to file a wrongful termination lawsuit against a previous employer

How long an employee has to take action against an employer for "wrongful termination" depends on the nature of the "wrongfulness". If the employee had a contract with his employer and the employer broke the contract, the employee has4 years from the date the company broke the contract to bring a lawsuit.  But beware, this time limit can be shortened by agreement. If an employee refuses to commit a crime and is fired for such refusal,  he has two years from the date of termination to bring a lawsuit. If an employee was fired for race, color, sex, age, disability, religion, national origin he has either 180 or 300 days from the day he was told he was going to be terminated to file a charge of discrimination with the Texas Workforce Commission or EEOC.  The 180 day deadline applies to state claims.  The 300 day deadline applies to federal claims.  However a single timely filing with either agency is sufficient to meet both deadlines. If a public employee was fired for Whistle-Blowing (there is no similar cause of action for non-government employees) he has 90 days to file suit (which may be extended by 30 or so days to allow internal grievance procedures to finalize) So, short answer, "it depends."