Many find the easiest way to figure the entries for Form. X is to first make the changes in the margin of the return they are amending.To claim a refund, you must file an amended return within 3 years after the date you filed your original return or 2 years after the date you paid the tax. You can find the CP or LTR number on the right corner of the letter. If you must amend an NPT return, complete a new tax return with the updated amount. Read the letter carefully. Most IRS letters and notices are about federal tax returns or tax accounts. Sending an IRS audit reconsideration request? Wage Tax refund requests must be submitted through the Philadelphia Tax Center. You don't need a username and password to submit a refund request.