The simplest way to track an interest only mortgage or loan is to set the
equal to the value of the loan when entering the loan information (this is different to a repayment loan, as you'd normally enter 'zero' there).
It is advisable to leave the interest rate blank when setting loans and mortgages up (unless you have a variable payment), as the way that some banks calculate interest rates might be slightly different to the way Money does. Money allows you to leave one of the parameters blank, as it can calculate one parameter based on the entries in the others. See the image below:
Money uses a daily interest rate method, and appears not to take much notice of public holidays - this means that it's calculations are rarely the same as the banks'. Expecting Money to produce down to the last penny calculations is unrealistic.
regarding some additional ideas on tracking an endowment policy.
has information on how to change particular parts (specifically the balloon amount) of a loan.
Keywords: loan, Endowment, interest, mortgage, ISA