A simple spring clean turned into a $2.5 million bonus for a Melbourne woman when she found a five-month-old Tattslotto ticket on her desk.

The woman, from suburban Doncaster, bought the ticket for the Superdraw on September 12 last year but thought she had lost it.

"I was just doing some spring cleaning and came across a ticket clipped to some other paperwork by a bulldog clip," the woman said.

"I knew West Doncaster News and Lotto had sold a division one winner, but I thought I had lost my ticket.

"Then I found it filed away yesterday and thought I'd call Tatts to see if I'd won anything. I really had no idea that it was the actual winning ticket."

She is one of two division one winners from that draw.

The woman plans to share some of her win with her family and put the rest in a term deposit to give herself time to think about what to do with her unexpected windfall.

"I lead a simple life and I intend to keep it that way," she said.

In May 2009, a Melbourne grandmother discovered that a Tattslotto ticket she had been carrying in her handbag for almost five months had won more than $1.3 million.

- AAP