How do I write the heading and date format in a CBSE formal letter?

Use the block format CBSE prefers. Start at the top left with the sender's address on two or three lines. Leave a line, then write the date in expanded form like 30 June 2026 (do not use 30/6/26). Next comes the receiver's designation and address, then the salutation 'Sir/Madam,'. After that, write the subject line in bold or underlined, beginning with 'Subject:' and kept short. Then the body in three paragraphs: introduction, details, and a polite closing request. End with 'Yours faithfully,' followed by your name on the next line. Keep every element left-aligned with no indentation. Neat, consistent format alone earns you the format marks even before the examiner reads your content.