On this Worksheet we find the allowed loss for each activity.
Allowed Loss = Total loss - Unallowed loss.
Column (a) is the total loss for the activity. It is calculated as the net loss for the current year (if there was loss this year) plus the prior year carryforward loss.
Column (b) is the unallowed loss for the activity.
Column (c) is the allowed loss--column (a) minus column (b).