1. If one is unaware or in doubt if a sin was committed, or
2. if one has been informed after (or between) the commission of acts – so that the act was definitely committed but in ignorance.
Ulla confronts the view that a “certain guilt offering” does not require previous knowledge:
if a man cohabits five times with a ‘betrothed bondmaid’ (forbidden in Lev. 19:21 – the assumption being he did not know she was engaged) he is liable to one [guilt-offering] only.
But, R. Hamnuna suggests a loophole:
If so, if one cohabits, sets aside a sacrifice (which is the first act of atonement), and states ‘Wait for me until I cohabit again’ – can he be liable for only one sacrifice?
Nice try, but no. The multiple guilt offering is only when there is a lack of knowledge or uncertainty. Once you know that the act is a sin, atonement is required for each act.
Let's be careful out there!