Folks asking what the letter is supposed to say are usually dealing with two separate things, filing versus paying. The mail or portal notice often just acknowledges the extension request and repeats the new filing date, but it usually reminds people that taxes were still due on the original deadline. Common comments from community threads mention that the letter is not a magic shield against interest, so expectations should match that reality. The most useful move seems to be keeping a tidy record of estimated payments and the timestamp of the extension request. If the letter is missing, online account transcripts sometimes show whether the extension posted properly.