According to Michael Roennevig, writing for the Houston Chronicle, writing a rebuttal letter requires using clear communication, gathering evidence and presenting that evidence as part of a formal rebuttal. This can be useful to keep certain information from having a negative effect on an individual personnel file at a workplace.
Before writing the rebuttal letter, attempt to speak with the person who originally wrote the document that requires a rebuttal. Clearly state polite disagreement with his appraisal and ask to discuss what led him to write what he has written. If he does not change his mind or reverse his decision after this conversation, consider whether the employer's review was unfair or not. If it was fair, there may not be much grounds for an official rebuttal, and writing one anyway may further create the impression of an employee who is a troublemaker. If there is grounds, consult with the company's Human Resources department on the form and requirements of an official rebuttal. Next, gather evidence, including positive statistics about job performance, that can help rebut the original document. Finally, write a letter of rebuttal to all appropriate parties that is not personal and quickly gets to the point. Cite the sections of the original document that are incorrect and offer the gathered evidence to disprove them. Keep the tone positive, but be sure to request that the rebuttal also be kept in the employer's personnel file in the event of future legal action.