The concept of acceleration is used to determine the amount owed under foreclosure. Acceleration allows the mortgage holder the right when the mortgagor defaults on the mortgage to declare the entire debt due and payable. In other words, if a mortgage is taken out on property for $10,000 with monthly payments required, and the mortgagor fails to make the monthly payments, the mortgage holder can demand the mortgagor make good on the entire $10,000 of the mortgage.
Virtually all mortgages today have acceleration clauses. However, they are not imposed by statute, so if a mortgage does not have an acceleration clause, the mortgage holder has no choice but to either wait to foreclose until all of the payments come due or convince a court to divide up parts of the property and sell them in order to pay the installment that is due. Alternatively, the court may order the property sold subject to the mortgage, with the proceeds from the sale going to the payments owed the mortgage holder.