Resignation letters are professional courtesies that extend your professionalism, even in the last days of current employment. Talk to the new company's HR and tell them that your previous company will issue you the experience certificate in 45 days time.The letter is a request from an employee to their former employer for an experience certificate. I have resigned on _____ date because ______(reasons). A sample form to document an employee's verbal resignation. Learn how to write a resignation letter (and what not to include) and then use our example letters as a guide.