A second mortgage is a loan taken in addition to the first mortgage. Subordinate to the first mortgage, these loans offer the borrower the ability to get money for home improvement, debt consolidation, or many other reasons without disturbing their first mortgage. The amount that can be borrowed is based on the difference between the current value of the property and the first mortgage and any other and any other outstanding loans secured by the property. Here again, there are many variations and interest rate structures available.