Yep, it is.
Using my excel calculator I put in a $100,000 mortgage at 2% interest.
Three separate cases:
- One with a 20-year amortization, monthly payment.
- One with a 15-year amortization, monthly payment.
- One with 20-year amortization, but extra payments to match the payment amount of the 15-year amortization.
You'll see that with the extra payments, it turns the 20-yr mortgage into the 15-yr mortgage. People will usually do this to give them extra flexibility if they have to stop making extra payments.