Dr Kathryn Fox is an Australian medical doctor and bestselling crime writer, best known for her forensic thrillers featuring pathologist Dr Anya Crichton. Drawing on her medical expertise, she crafts gripping, authentic crime fiction and is also a passionate advocate for forensic medicine education and public engagement.

“I was getting ready for work and picked up the milk from the fridge. The carton slipped out of my hand and spilled all over the carpet. If I’d left it there all day the smell would have made me sick when I got home. So I stayed to clean it. I’m going to need a sick certificate.”

Of course, this patient arrived late that afternoon as an “urgent appointment”. Their boss had messaged asking for proof that they had, in fact, been sick on a Monday.

It turns out ‘chucking a sickie’ is remarkably common.

An iSelect survey of 1,000 Australians found that 70.8 per cent admitted taking at least one sick day in the past year for reasons other than physical illness.

Even when mental health days were excluded – which are increasingly recognised as legitimate personal leave – 68 per cent still admitted to chucking a sickie.

The likelihood decreases with age, presumably as workplace responsibilities increase, or because older workers are more likely to be employers or managers. Those most likely to admit to taking a sick day without illness? People aged 25 to 34.

This may explain why more employers now request medical certificates even for single days off. Many people assume certificates are only required after several days of absence, but it’s ultimately up to the employer to set the rules.

The result is that doctor’s appointments are often taken up by patients who aren’t there for diagnosis or treatment, but simply for paperwork. That makes it harder for people with genuine illness to get an appointment when they really need one.

It also places doctors in an awkward position.

Writing a certificate for something that isn’t true isn’t just bending the rules – it can be considered fraudulent and could jeopardise a doctor’s registration. Refusing, however, often leads to anger. Patients may insist the doctor is costing them a day’s pay – or even their job.

Genuine mental health days and carer’s leave are increasingly recognised as legitimate personal leave. The problem arises when doctors are asked to certify illnesses that never existed.

Occasionally the story simply doesn’t hold up.

I once saw a patient who claimed they had been home all day with diarrhoea. Unfortunately for the story, they arrived with fresh sunburn, clear singlet and sunglass lines, sand on their clothes and the unmistakable smell of the ocean.

Not exactly someone who had spent the day between the bedroom and bathroom.

Back-dating certificates is another common request. Someone takes a day off, returns to work, and when the boss becomes suspicious – sometimes after seeing photos of the ‘sick-day’ activities on social media – they present at the doctor’s surgery demanding a sick certificate.

Medical certificates can’t simply be written after the fact. Doctors can certify illness only if they have assessed the patient at the time or if there is a clear ongoing condition being treated.

It’s often surprising how honest people can be about their plans.

Some of the explanations I’ve heard include:

“I’m owed a lot of sick leave, so I decided to take a week off to work on renovations.”

“I need to pick up a new car. Why should I go on a weekend when I can take a sick day?”

“I partied all weekend. I need another day to recover.”

And one personal favourite:

“I needed a sick day because my friend’s cat died.”

I asked if they had spent much time with the cat.

“Well, no,” the patient replied matter-of-factly. “I’m allergic to cats. But I’m very close with my friend.”

Some stories are almost impressive in their creativity.

One regular visitor to the emergency department used to appear during cricket Test matches complaining of a sore finger. He’d sit in the waiting room watching the game on television. When the doctor called him in, he’d simply rejoin the queue so he could keep watching. Eventually he would be seen, receive a certificate, and go home having enjoyed the match – while his wife believed he had spent the day at work.

Then there are the cases where a day off unexpectedly becomes a genuine medical problem.

One patient hobbled into the clinic after a romantic day at the beach. She admitted she had skipped work to visit a nude beach with her boyfriend. While wading into the water she slipped on the rocks.

She had come in asking for a certificate for the day she’d taken off.

Instead, she left in a moon boot with an X-ray confirming a fractured ankle – and six weeks off work.

Sometimes it just doesn’t pay to chuck a sickie.