Sefer Ha’mitzvos Ha’Katzar (The concise book of mitzvos)
By the Chofetz Chaim
This book lists the Torah mitzvos that can be observed today
First Section – the Positive Commandments
64. It is a positive commandment to cancel a loan during the Shmittah year (which occurs once every seven years)
As it states in Devarim (Deuteronomy) 15:2, "Anyone who has given a loan is to cancel what he has lent." If the borrower repays the loan obligation after the Shmittah year, the lender should not accept it from him. He should say to him, "I release the loan," as it states in Devarim, "This is the law of Shmittah." If the borrower says back to him, "Nevertheless, I still want you to take it," then the lender can take the repayment.
According to Torah law, the cancelling of money obligation only happens during the time when the Jubilee year (once every 50 years) is celebrated [Jubilee year is not celebrated nowadays]. According to our Sages, the cancelling of money obligations occurs even nowadays, so we do not forget the Torah law of Shmittah. A prozbul [a declaration in court that Shmittah is not to cancel a loan] is effective nowadays making it that Shmittah does not cancel money obligations.
This applies to men and to women.