* Solid Minerals interest rates are calculated as simple interest.

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I = Interest due A = Assessment amount R = Annual interest rate N = Number of days in the year n = Number of days (compounding periods) late

For interest owed to MMS, calculate that interest from the due date of the sales month to the date MMS received the payment. For interest MMS owes you, calculate that interest from the due date of the sales month, without regard to an extended due date because of an estimate, to the date MMS receives Form MMS-2014 recouping the overpayment. The overpayment interest rate is currently one percent less than the underpayment interest rate. Both rates are compounded daily.

COMPOUNDED DAILY INTEREST FORMULA EXAMPLE
USING TWO INTEREST PERIODS

Interest Amount = Assessment amount x ((1 + Annual interest rate/Days per year)     ^{No. of days late}  - 1)

Calculate interest on $1,382.62 for 60 days at 9%
$20.60 = $1,382.62 x ((1 +.09/365)⁶⁰ -1)

To calculate interest on $1,382.62 for 60 days at 9% and then 90 days at 11%, follow Steps 1 through 5, then:

Total interest due is $59.17 ($20.60 + $38.57)

Please note that the $20.60 interest calculated at 9% is added to the $1,382.62 assessment amount before multiplying by the 11% factor for the subsequent interest period.  The calculated interest for each period must be added to the assessment amount and becomes the new assessment amount for each additional interest period.

If you have interest calculation questions, please call Financial Management Services at
1-800-433-9801.