(a) Additional interest based on net appreciated value. Any mortgage for which the mortgagee has chosen the shared premium option (§206.107) may provide for shared appreciation. At the time the mortgage becomes due and payable or is paid in full, whichever occurs first, the borrower shall pay an additional amount of interest equal to a percentage of any net appreciated value of the property during the life of the mortgage. The percentage of net appreciated value to be paid to the mortgagee, referred to as the appreciation margin, shall be no more than twenty-five percent, subject to an effective interest rate cap of no more than twenty percent.

(b) Computation of mortgagee share. The mortgagee's share of net appreciated value is computed as follows:

(1) If the outstanding loan balance at the time the mortgagee's share of net appreciated value becomes payable is less than the appraised value of the property at the time of loan origination, the mortgagee's share is calculated by subtracting the appraised value at the time of loan origination from the adjusted sales proceeds (i.e., sales proceeds less transfer costs and capital improvement costs incurred by the borrower, but excluding any liens) and multiplying by the appreciation margin.

(2) If the outstanding loan balance is greater than the appraised value at the time of loan origination but less than the adjusted proceeds, the mortgagee's share is calculated by subtracting the outstanding loan balance from the adjusted sales proceeds and multiplying by the appreciation margin.

(3) If the outstanding loan balance is greater than the adjusted sales proceeds, the net appreciated value is zero.

(4) If there has been no sale or transfer involving satisfaction of the mortgage at the time the mortgagee's share of net appreciated value becomes payable, sales proceeds for purposes of this section shall be the appraised value as determined in accordance with procedures approved by the Commissioner.

(c) Effective interest rate. To determine the effective interest rate, the amount of interest which accrued in the twelve months prior to the sale of the property or the prepayment is added to the mortgagee's share of the net appreciated value. The sum of the mortgagee's share of the net appreciated value and the interest, when divided by the sum of the outstanding loan balance at the beginning of the twelve-month period prior to sale or prepayment plus the payments to or on behalf of the borrower (but not including interest) in the twelve months prior to the sale or prepayment, shall not exceed an effective interest rate of twenty percent.

(d) Disclosure. At the time the mortgagee provides the borrower with a loan application for a mortgage with shared appreciation, the mortgagee shall disclose to the borrower the principal limit, payments and interest rate which are applicable to a comparable mortgage offered by the mortgagee without shared appreciation.