1.  To modify the whole letter, wait until you complete the rest of the tax return, and go to Screen 5.2, custom client letter.

OR

2. Make minor changes on Screen 5.1 Invoice/Letter

OR

3. To add a paragraph (or 2) to the end, go to Screen 47 Notes, and click on Letter Misc 1 (inserts at beginning) or Letter Misc 2 (inserts at end).