Neither. Go to Mesabi Trust website and click on "Tax Guide" and follow their instructions. I choose to report according to the Tax Guide and I do not use the 1099 info supplied by the brokerage which holds the units. The latter has been the broker's best efforts, but wrong. If and when I might be audited, I can then point to the definitive Mesabi Tax Guide as support, rather than the broker's unsubstantiated numbers. After holding the units for a year there are considerable tax advantages. But beware buying multiple lots as the difficulties get compounded. Good luck.
My 1099 has always been wrong for MSB.
They use the Section 1231 capital gains rules even for units purchased within the last year.
Have to write a note attached to my tax return each year explaining the discrepancy.