Home Equity Loan

Hi:

I have a loan with a $20,000 principal balance at 4.65%, 5 years. Using the IPMT function the monthly payments are $374.23. However, I do not make constant payments. For example, my first three payments were $535, $1400 and $461 on 10/11/11, 11/9/11 and 12/9/11, respectively. Is there any way to keep tarck of a loan where payments are not constant. All my payments will be more than the required amount. Is the difference between my payment and the actual amount applied all to principal?

Thanks