A teacher has given the ultimate gift to her former school, leaving $1 million (approximately $1.3 million AUD) to her students in her will.

It came as a shock to all that Genevieve Via Cava was a secret millionaire.

Over the years she cut out coupons and wore the same clothes nearly every day – all to save money.

The special needs teacher passed away in 2011 but the school community in Dumont, New Jersey, received the surprise cheque only recently.

Friend Richard Jablonksi says no-one knew Via Cava had so much money, only that she was frugal and never went on holidays.

"[She was] generous and big hearted towards kids," Jablonksi told CBS New York.

She had no immediate family, so when she died Via Cava left her home and contents to Jablonksi, but the rest of her estate went to the Dumont School District.

"She must have had a tremendous connection with the district and the students," Dumont Public Schools Superintendent Emanuele Triggiano says.

Via Cava spent her entire career working with children who have special needs, he says.

"The most we've ever seen from any group was maybe in the tens of thousands but never something like this," Triggiano says.

The money will be invested and the interest used to fund an annual scholarship, worth $25,000, to help children further their education.

Friends say Via Cava continued to keep in touch with her former school after retiring in the 1990s, even helping some students find work after graduation.

The penny-pinching teacher also left $100,000 to other organisations, including an animal refuge and the Salvation Army.