If your carryover losses are $100k and you add $1, then you are at-risk for this $1 and only the $1.
When you check the box that you are at-risk, then you are telling TT that you have sufficient at-risk (basis) to absorb all $100k; the language says "all of my investment is at-risk".
You being active, cannot have "at-risk carryover loss" as for you they are mutually exclusive. You would have carryover loss due to at-risk limitations (no at-risk).
TT is asking you exactly what needs to be asked "what portion of the carryover loss is covered by basis / at-risk". That is all you are entitled to deduct.
By way of example: Suppose you have $100k carryover loss due to no basis / at-risk. Your K-1 reflects $50,000 of current year income. You are entitled to use $50,000 of the carryover since you are now at-risk for that $50,000. This will net to zero taxable income and you will also now have zero basis with $50k carryover loss.
*A reminder that posts in a forum such as this do not constitute tax advice.
Also keep in mind the date of replies, as tax law changes.
