Note 2. Net income per unit is based on 13,120,010 units outstanding during the period.

The Trust accounts for revenue in accordance with ASC 606, Revenue from Contracts with Customers. All revenue is recognized as the performance obligations are satisfied.

Disaggregation of Revenues

The following table represents a disaggregation of revenue for the three and nine months ended October 31, 2018 and October 31, 2017:


	Three Months Ended October 31,
	2018		2017
Base overriding royalties	$	8,349,255	$	6,655,167
Bonus royalties		5,422,575		4,136,894
Fee royalties		119,443		106,554
Total royalty income	$	13,891,273	$	10,898,615


	Nine Months Ended October 31,
	2018		2017
Base overriding royalties	$	23,652,703	$	16,560,379
Bonus royalties		15,572,478		12,960,058
Fee royalties		437,831		368,781
Total royalty income	$	39,663,012	$	29,889,218

Base overriding royalties

The performance obligation for the base overriding royalty consists of providing Northshore Mining Company (“Northshore”) access to the Peters Lands, Cloquet Lands, and Mesabi Lands and the right to mine on these lands. The consideration to be received from this access relates to the volume of iron ore shipped by Northshore. Mesabi Trust receives royalties at the greater of (i) the aggregate quantity of iron ore products shipped that were mined from Mesabi Trust Lands, and (ii) a portion of the aggregate quantity of all iron ore products shipped from Silver Bay that were mined from any lands, such portion being 90% of the first four million tons shipped from Silver Bay during such year, 85% of the next two million tons shipped during such year, and 25% of all tonnage shipped during such year in excess of six million tons. The royalty percentage paid to the Trust increases as the aggregate tonnage of iron ore products shipped, attributable to the Trust, in any calendar year increases past each of the first four one-million ton volume thresholds. The base overriding royalties contain variable consideration, as the transaction price is based on a percentage that varies based on the total cumulative tons of iron ore shipped for the calendar year. The Trust estimates the variable consideration it expects to be entitled to receive over the contractual period associated with royalty agreement, which resets the royalty percentages at the beginning of each calendar year. The Trust evaluates the estimate of the variable consideration to determine whether the estimate needs to be constrained; therefore, the Trust includes the variable consideration in the transaction price only to the extent that it is probable that a significant reversal of the amount of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. For the base overriding royalties, the Trust estimates the base overriding royalty percentage using the expected value method, which calculates the estimate based off the historical, current, and forecasted shipments. The Trust recognizes base overriding royalties on a quarterly basis based on the actual shipments for the fiscal quarter at the estimated royalty percentage as described above and based on the estimated prices for iron ore products sold under the Cliffs Pellet Agreements.

Bonus royalties

The performance obligation for the bonus royalties consists of providing Northshore Mining access to the Peters Lands, Cloquet Lands, and Mesabi Lands and the right to mine on these lands and the consideration to be received from this access relates to the volume of iron ore shipped by Northshore. The Trust recognizes bonus royalties on a quarterly basis based on the actual shipments of the fiscal quarter at the actual royalty percentage for those shipments and based on the anticipated prices for iron ore products sold under the Cliffs Pellet Agreements.

Fee royalties

The performance obligation for the fee royalties consists of the volume of crude ore mined on a quarterly basis. The Trust recognizes fee royalties on a quarterly basis based on the actual crude ore mined during the fiscal quarter.

Accrued income receivable

The accrued income receivable is included in net income per unit. The Trust recorded $6,110,966 of accrued income receivable as reflected on the Condensed Balance Sheet as of October 31, 2018 (unaudited). As of January 31, 2018, the Trust recorded accrued income receivable of $1,956,091. Accrued income receivable is accounted for and reported for the Trust’s fiscal quarter based on shipments during the month of October at estimated prices for iron ore products sold under the Cliffs Pellet Agreements, even though such accrued income receivable is not available for distribution to the holders of Certificates of Beneficial Interest in Mesabi Trust (“Unitholders”) until the applicable royalties are actually received by the Trust. Accrued income receivable also includes accruals for anticipated pricing adjustments, which can be positive or negative.

Contract asset

A contract asset in the amount of $1,362,897 is reflected on the Condensed Balance Sheet as of October 31, 2018 (unaudited). As of January 31, 2018 the Trust recorded a contract asset of $99,264. The contract asset is based on the revenue recognized on the base overriding royalties, at the estimated prices for iron ore products sold under the Cliffs Pellet Agreements, that will be collected in subsequent quarters as the uncertainty associated with the variable consideration is resolved. The contract asset is not available for distribution to the Unitholders until the applicable royalties are actually received by the Trust. The Trust includes estimated future royalty rates on current contracted volumes within contract asset.

Contract liability

The contract liability represents an estimate of decreases in royalty revenue related to tons of iron ore that were shipped by Northshore, but for which Northshore has indicated that final pricing is not yet known and is adjusted in accordance with the Trust’s revenue recognition policy each quarter as updated pricing information is received.