It's Pay Day where we ask Australians the money questions we don't like to talk about. We aim to demystify personal finance and normalise conversations about what we earn and how we save it — or spend it.

If you were asked to picture a scientist you might picture someone in a lab, head down, white coat and goggles on — but Dr Catriona Nguyen-Robertson's science career took her in a different direction. After training in immunology at the Peter Doherty Institute for Infection and Immunity, Catriona moved into science education and outreach and is now more likely to be found performing and singing about everything from the immune system to the universe under the moniker Dr Cat AKA The Singing Scientist.

For Pay Day Dr Cat discusses juggling multiple jobs, her guilty science-themed splurges, and how bubble science is helping her fundraise for a voyage to Antarctica.

How would you describe your financial situation right now?

I have never had a full-time job. But working across multiple part-time and casual jobs, I end up working more than the equivalent of full-time. Together, they allow me to live comfortably without worrying about my finances.

I try to be thrifty, as that's how I was brought up, but I will also happily spend a bit of money on presents or food for friends, or go out from time to time. Sometimes I wonder whether I need to be working so much — and I am trying to be more mindful of ensuring I have proper breaks — but I'm now used to this more comfortable financial position and I genuinely love all of the science education and outreach that I get to do with those jobs.

How was money spoken about in your house growing up?

There were two quite different approaches from my two parents. My mother grew up very wealthy and then lost it in the Vietnam War. She arrived in Australia with absolutely nothing except the clothes she wore. She instilled in me a dislike of unnecessary expenses because it is always better to save if you can — although, sometimes her classification of what was "unnecessary" could sometimes be extreme. My dad, on the other hand, grew up without much money, and was always happier to buy things with the money that he had earned.

What did you spend your first pay cheque on?

Honestly, it went straight into the bank. I grew up receiving lì xì (lucky money) at New Year and my mum encouraged me to funnel it all into a bank account. When I got a job in high school, that helped grow my savings as I never touched my pay. Having said that, I spent pocket money from chores on the odd bubble tea with my mates after school.

About how much of your income goes towards your rent or mortgage each week?

Because of my multiple jobs, essentially all my income from one job (three to four days a week) goes into the mortgage and I have the income from my other jobs to spend on other things. When I can, I try to put any extra into the mortgage.

What's your guilty splurge?

Fun, quirky clothes. I don't like to spend too much on clothes, as I was raised on hand-me-downs from older cousins and that suited me just fine. I also buy fabric on sale to send to a Vietnamese auntie whenever any of my family goes back to have dresses made for me. But every now and then, I'll see a great science-themed dress and I'll splurge. I have dresses with chemical formulae, galaxies, DNA, and more. It's all very "Ms Frizzle".

Have you ever kept a secret about money?

For a long time, I felt uncomfortable telling people that I own the house I live in. And so didn't. I felt awkward about owning a house at a reasonably young age because I am aware of how much of a privilege it is.

Honestly, it was a few fortuitous circumstances that came together. I could only afford it thanks to the combination of my mother inheriting money from the sale of her father's one remaining property in Vietnam, and my family being friends with a neighbour selling their house, who wanted to sell to me specifically as she loved the idea of me living close to my mother in her older age. While I had been saving for years, I definitely wouldn't have earned enough otherwise — certainly not on a measly PhD stipend! Now that more of my friends are purchasing houses of their own, I feel a bit more comfortable.

How much was the last loaf of bread you bought?

Only $1.99 for a decent loaf of sourdough! The supermarket near me puts a trolley out of discounted bread that is "best before" that day. It's not fresh but perfectly fine for toast and freezer bread.

How many bank accounts do you have? How do you organise your money?

I have two accounts: an everyday account that offsets my mortgage and a home loan account. Before the mortgage, I had a high interest savings account, and I would always transfer anything that I didn't need into that account. Let whatever money you have help you make money.

What are you saving for right now and how are you doing it?

I've been putting aside money to save for the Homeward Bound program — an incredible but very costly opportunity to travel to Antarctica with other women and non-binary people in STEMM (science, technology, engineering, mathematics, and medicine). 

I ran a bubble science show at a children's birthday party in return for a donation, and it was really fun — plus the children and adults enjoyed themselves. (If you or anyone else in Melbourne wants a show that involves playing with bubbles and a fog machine with a bit of science mixed in, please hit me up.) I am also running fundraisers at the Melbourne Planetarium, where I guide people through the solar system, among stars, and to the edge of the observable universe and back.

What's the biggest lie you tell yourself about money?

"That's unnecessary." My mother's voice rings in my head sometimes when I'm considering a purchase but wavering because of its cost.

Perhaps my view of expenditure isn't the healthiest — or the safest. For example, I usually opt for walking whenever I'm away from home as the cheapest — well, free-est — mode of transportation. It's a great way to explore new cities, but I probably shouldn't be walking great distances through a new city alone late at night.

I need to be more comfortable to bite the bullet and spend money a little more.

If you could tell 18-year-old you one thing about money, what would it be?

Track your finances properly! Don't wait until you have "everything in order" or set up the "perfect spreadsheet". You don't need complex Excel formulae or to be too hard on yourself, just start by paying attention to the money coming in and the money going out (especially when dealing with cash).

Dr Cat AKA the Singing Scientist is a science educator who has worked with Scienceworks, Museums Victoria and other national outreach programs. In January 2025 she will be joining the Homeward Bound voyage to Antarctica with women and non-binary people in STEMM. She will be holding a tour through the universe at the Melbourne Planetarium this Saturday.