Joanne, 48, raised daughter Jessica, now 20, as a single mum after splitting from her husband Jorge Arantes in 2003, four months after Jessica's birth, and just over a year into their marriage. The family had been living in Portugal, and Jo moved with her baby daughter to Scotland.
She told the charity her 'much-wanted daughter had been conceived and born while I was married, but the failure of that relationship saw me living shortly afterwards on state benefits in the coldest winter Scotland had seen in quite a few years'.
"I had imagined that I would be back at work fast," she writes. "Indeed, it was because I expected to be employed outside of the home again that I was working so hard to finish the children's novel I never told anyone I was writing (not wishing to be told that I was deluded). As it turned out, my belief I would shortly be back in paid work turned out to be a much bigger delusion than the hope that the novel might be published."
Jo says that she was told she would never get state-funded childcare for Jessica because she was 'coping too well'.
She eventually ended up taking an admin job for a few hours each week at a local church, where she was paid exactly the amount she could keep without losing her benefits: £15.
"My overriding memory of that time is the slowly evaporating sense of self-esteem, not because I was filing or typing – there was dignity in earning money, however I was doing it – but because it was slowly dawning on me that I was now defined, in the eyes of many, by something I had never chosen. I was a Single Parent, and a Single Parent On Benefits to boot," she writes.
She said that the 'patronage' was almost as hard to bear as stigmatisation, and recalls how one woman referred to her - in her earshot - as 'The Unmarried Mother'.
She says that even after her success as an author, the 'Single Parent tag' still followed her and she became the 'Single Parent' writer who wrote Award Winning Books/Got Film Deal.
Jo concludes that she would tell 'any single parent currently feeling the weight of stereotype or stigmatization' that she is 'prouder' of her years as a single mother than of any other part of her life.
"Yes, I got off benefits and wrote the first four Harry Potter books as a single mother," she writes. "But nothing makes me prouder than what Jessica told me recently about the first five years of her life: 'I never knew we were poor. I just remember being happy'."
In 2001 JK Rowling married anaesthetist Neil Murray and went on to have two more children, David, now 10, and daughter Mackenzie, eight.