The Equality and Human Rights Commission is urging employers from medium-sized voluntary sector organisations to take part in an online survey as part of its research into their measuring and reporting of the gender pay gap.
The EHRC wants recruitment staff at organisations that have between 250 and 500 employees to complete the survey.
Alan Christie,director of policy for the private sector at the EHRC, said charities of this size did not often have the time and resources to take part in a detailed consultation.
The EHRC launched the exercise in August to develop a way for private and voluntary sector employers to measure the gender pay gap. Women's median pay is 12.8 per cent less per hour than men's, and there has been no improvement in the past three years.
"We have received a positive response to our consultation process so far," said Chritsie. "We want to ensure all businesses and voluntary organisations have the opportunity to tell us what sort of gender pay gap reporting they would prefer and to highlight any issues they have with it."