At the end of the loan term there is still a remaining principal
loan balance and the mortgage company generally requires that the
loan be paid in full, which can be accomplished by refinancing.
Many companies have other options such as a conversion feature at
the end of the term. For example, the loan may convert to a 30 year
fixed loan at the thirty year market rate plus 3/8 of a percentage
point. Your conversion can be guaranteed based on certain criteria
such as having made your last 24 payments on time. The balloon mortgage
program with the conversion option is often called a 7/23 Convertible
or 5/25 Convertible.