A woman accused of scores of child sex offences on the New South Wales Central Coast has pleaded guilty in the Gosford District Court. 

Julia Ann Bamforth, 49, has been charged with 67 counts relating to child sex abuse.

In the Gosford District Courton Friday she pleaded guilty to all child sex offence charges, nearly 40 of which related to her having sexual intercourse with a young boy.

It is alleged Ms Bamforth sexually abused the boy, who lived with a cognitive impairment, on dozens of occasions over a five-year period.

Police allege the abuse took place from when the boy was 12 years old. He is not related to Ms Bamforth.

According to court documents, the teenager told police that he was given "free pot, free ice, [and] free MDMA" in exchange for sex during the five-year period.

Police have also alleged that more than 20 of these offences took place in the company of Ms Bamforth's husband, 50-year-old Paul Robert Bamforth.

Mr Bamforth has been charged with similar offences but the court heard on Friday that he has applied to change some of his pleas from guilty to not guilty.

His matter is now being dealt with separately.

Both Paul and Julia Bamforth had pleaded guilty to all charges in a local court last year but had not officially been arraigned in the district court.

Judge David Wilson told the court that both of them should have been arraigned when the matter first came before the district court.

Mr Bamforth is due back before Gosford District Court on March 2 to be arraigned.

Child abuse material found in search

On Friday, the court heard that some of the abuse had allegedly been filmed.

Police executed a search warrant of the Bamforths' Narara home on February 26, 2021.

Court documents tendered on Friday in relation to Ms Bamforth show that police found nearly 90 videos containing child abuse material involving the boy on USBs and laptops from the couple's property.

According to the court documents, during the search, police seized items such as methylamphetamine, tasers, a zombie sword, and external hard drives.

The documents also allege the couple had texted about the abuse, which showed that they were aware of his "cognitive impairment".

Police allege 300 notes on one of the phones seized also contained explicit stories, which suggested the couple had a predisposition to having sex with young children.

The Crown's submissions in relation to Ms Bamforth's matter said that it was "hard to imagine a worse case" and that the seriousness of the matter was in the high range.

The defence argued that the matter was not the worst case he had seen and that the matters were instead "well above the mid-range" of seriousness.

Ms Bamforth is due back before the court on February 22 before the matter can proceed to sentence.

She has been ordered to appear in person.

The pair remain in custody.