you bought into a partnership. under partnership tax rules its income/loss is allocated on a per share/per day basis so you will be receiving a k-1 (that's how a partnership reports the results to its partners, and the IRS gets a copy) that will report your share of income or loss for the period you held it. that income or loss affects your tax basis. However, the broker receives no partnership information and so cannot properly adjust the basis it reports on the 1099-B. as a matter of fact the type on the 1099-B will be type B - proceeds but not tax basis reported to the IRS. the k-1 package will include a supplemental schedule to allow you to correctly report the gain or loss on sale. if you don't include the k-1 on your tax return, you might get a letter from the IRS which could be a few years after filing. it may also be true that the income loss is so small the IRS won't bother you if you don't report it. no way to know and i don't suggest or recommend not reporting taxable events.
