Fasting: Believing an Act Does Not Invalidate the Fast
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 1629
If someone performs one of the things mentioned [in the previous ruling] while believing with certainty that it would not invalidate his fast, then kaffārah is not obligatory for him. The same applies to someone who does not know that fasting is obligatory for him, such as a child in the early stages of legal responsibility (bulūgh).