Your cost basis on the 1099-B (if its there) may be incorrect, but you still report the sale in the 1099-B section and merely indicate disposal within the K1 section itself. The reason the 1099B is usually not complete is because the basis is impacted by income and loss per the K1 forms while you had owned the units. Cumulative adjustments to basis suggests losses on K1, which lower your basis. However, the numbers you typed don't make too much mathematical sense. $7500 basis (10k less 2.5k) sales process of $500 resulting in gain of $600?
