I've taken on a few new clients from a practice that DID NOT perform any basis calculations on prior returns. Some of these entities go back for many years (20 plus years). Many of these S corps have distributions and or losses in 2020 which requires a basis calculation to be submitted with their personal returns. In many instances, even without the requirement I'm left wondering if the S corp owner still has any basis left to take losses. Invariably these clients do not have their records from many of these prior years. For example, they may have returns starting in 2010 but the S-corp inception date was 2002.
Of course, to calculate basis accurately, I would need every return but they are not available. I'm soliciting opinions as to what one would do in these circumstances.
Thanks