Unfortunately it's a mixed batch of 6 lots purchased and sold at different times. I have good records for my purchase and sales price for all of them. However, my understanding is that the true cost basis is calculated based on the Sales Schedule in my K-1, not what my brokerage reported. In the sales schedule they have filled in the columns for
(5) Cumulative Adjustments to basis (some of these are negative and some are positive)
(7) Ordinary Gain
(9) Alternative Minimum Tax Basis Adjustment
So for example one of my line items on the sale schedule is when I sold 455 units and I need help figuring out my actual cost basis to report on the 1099-B as you suggest:
(3) Sales proceeds: 500
(4) Purchase amount: 10,000
(5) Cumulative Adjustments to basis: -2500
(7) Ordinary Gain: 600
(9) Alternative Minimum Tax Basis Adjustment: -162
