What is a confirmation letter?
A confirmation letter is the document an employer gives you when your probation period ends successfully and your employment becomes permanent. It states the date of confirmation and any change to your terms. Without it, ask HR in writing whether your probation has ended or been extended.
What it usually contains
A confirmation letter normally gives your name and designation, the date your probation ended, the date your confirmation takes effect, and whether pay, notice period or benefits change from that date. Some companies issue it automatically, others only after a manager review. If your probation was extended, you should receive that decision in writing too.
Why it matters
Notice period, leave entitlements, and eligibility for some benefits can depend on confirmed status under your contract. Keep the letter with your offer and appointment letters, because a later employer may ask for employment documents.
Example
An employee joins with a six-month probation. In the sixth month her manager signs off on her review, and HR sends a letter confirming her as a permanent employee from the next day with the same designation and an updated notice period.