The findings are consistent with studies in Europe and the US which have also identified a "robust and persistent" wage penalty for gay men.

"There are grounds for concern that workers in Australia, particularly gay men, are discriminated against because of their sexual orientation," Ms La Nauze's paper concludes.

The wage disparity between gay and straight men identified by Ms La Nauze's modelling is strikingly similar to the gender wage gap – the long standing gulf between average full-time earnings of men and women. Wages data released on Thursday showed the gender pay gap in Australia has reached a record 18.8 per cent. On average, a man working full-time earns nearly $300 a week more than a female full-timer.

However, Ms La Nauze found the negative pay gap experienced by gay men relative to heterosexual men does not apply to gay women. Instead gay women enjoy a wage premium of up to 13 per cent compared with heterosexual women. Ms La Nauze says one possible explanation is that gay women are rewarded because their employers have a perception that they are less likely to leave the workforce to have children than heterosexual women.

"If employers believe heterosexual women are more likely to have children, or are more likely to take on a higher proportion of child-rearing duties, and if employers believe this results in lower productivity, then heterosexual women may be penalised and receive lower wages than lesbian women," she said.