Australians claim about $23 billion in tax deductions for work-related expenses each year. Credit:Erin Jonasson Women already suffer a full-time earnings gender pay gap of about 16 per cent in this country. Turns out, we're making things even worse when it comes to tax time. A new research paper for the ANU's Tax and Transfer Policy Institute has identified a "gender deductions gap".

Using Tax Office data from 2013-14, research fellow Peter Varela found that men, on average, claimed total deductions against their income of $3218 a year, compared with $1916 a year for women. In these raw average terms, men out-claimed women in nine out of the 10 deduction classes – with men and women claiming exactly the same for self education expenses. For instance, men claimed $877 a year for work-related car expenses, compared with $433 for women. They claimed $242 a year for travel – including meals and accommodation for overnight travel – versus $80 for women. Now, it's important to make sure we are comparing apples with apples.

The average male worker declares a higher income than the average female, so one would expect a higher level of deductions by men. But using various methods, Varela was able to splice and dice the figures to control for gender differences on income, occupation, professional status and relationship status. Even after allowing for those factors, Varela found a gap of about 12 per cent in what men and women claim. "In other words, if there is a man and a woman who both earn the same amount of income, work in the same occupation and are the same age, the man will generally claim more deductions than the woman. The paper finds evidence that this gap exists, and is reasonably large. "When evaluated at the mean level of female income and deductions, this equates to approximately $240 of deductions, which at a marginal tax rate of 32.5 per cent changes take home income by around $75 per year."

Interestingly, many Aussie men and women ignore Packer's advice, claiming zero deductions on their tax returns. But more women are more likely than men to claim zero. At the top end of the tree, the Packer effect is real – but only for men. "There is a significant mass of high deduction individuals in the male distribution that is not apparent in the female distribution," Varela says. So why are women worse (or better) than men at claiming deductions? That is open for speculation, but possible reasons, according to Varela, include: "men being more willing to risk audit, men having more information about the deductions available to them, men being more willing to maintain the documentation needed to claim deductions, and men being entitled to more deductions in a way that is not captured by observable characteristics".

So, ladies, it's time to get claiming. Since last doing my tax, the Tax Office has released a new smartphone app, myDeductions, that allows you to log "point to point" work-related car trips using Google maps. Just remember you can't claim the journey from home to your ordinary place of work. As for handbags, the Tax Office last year clarified that women may be just as entitled to make a claim for the work-related use of a handbag, just like a briefcase. Loading You need to keep a log book of your usage, and claim only for bags which could plausibly be work related – so clutches are out of the question. Also, if the bag costs more than $300, you will be required to depreciate it over a number of years.

If Packer were a woman, he'd have done it.