If you have a $300 million dollar loan with 6% interest over 25 years and at the end of 15 years the loan and accumulated interest will be forgiven, how would you account for it at the end of the 15th year?

If you have a $300 million dollar loan with 6% interest over 25 years and at the end of 25 years the loan and accumulated interest will be forgiven, how would you account for it at the end of the 25th year?