The reason you should always check your receipt after the supermarket checkout.

Heading to the supermarket is something we do so regularly that we often go into autopilot as we stroll the aisles, select our items and pay for everything. This also means that we often forget to check our receipts. While it may seem trivial, checking your receipt will prevent you from being overcharged at the checkout – and you’d be surprised at just how often this happens!

Whether an advertised discount wasn’t applied or an item was scanned twice, there are multiple reasons why we may be accidentally forking out too much at the supermarket without even realising it.

A new finder.com.au study showed that although 76% of Australians check their supermarket receipt for discrepancies, on average, they need to be overcharged by $10.50 or more before they’re prompted to ask for a refund.

Looking to save money at the supermarket? This mum feeds her family for $42 a week. (Post continues after audio.)

Surprisingly, those with adult kids (82%) are the most likely to check their receipt, followed by those with teen kids (78%) and those with young kids (76%). Women are marginally more diligent when it comes to reviewing their docket, with 78% checking over their receipt compared to 75% of men.

In terms of how frequently we’re overcharged, the research revealed that 40% of us have been overcharged at the checkout in the last year. Of those overcharged, the average Aussie received an incorrect bill three times in 12 months, while 5% were overcharged over six times.

If you’ve been incorrectly charged at the supermarket, here’s what you need to do:

1. Hold onto your docket.

To request a refund, you’ll need proof of purchase, so make sure you hold onto your receipt so you can present it to the supermarket upon your return. If possible, ask to speak to the store manager to speed up the process.

If you have any supporting payment evidence, such as the transaction details through your online banking account, this may come in handy too.

Even after you've left, hold onto your docket. 

2. Know your rights (the freebie guarantee).

According to the Australian Competition and Consumer Commission (ACCC), you can ask a business for a free repair, replacement or refund if there’s a major issue or defect with the product, or if you’ve been incorrectly charged.

Under the Scanning Code of Practice, if an item is scanned incorrectly, you’re entitled to pocket it for free. Currently, Woolworths honours this code while Coles and Aldi have their own versions of it. See what guarantee applies at your favourite retailer.

3. Act quickly.

If you want to request a refund, you’re not bound by a specific timeframe. It’s up to the retailer’s discretion, but the sooner you act the better.

4. Remain calm.

When you approach the supermarket, stay calm. Clearly outline the problem and request a refund. If they’re not willing to budge, you can remind them of your right to a refund or replacement.

In the worst case scenario, you can lodge a complaint with the ACCC (but let’s hope it doesn’t come to that!).

When you visit your local supermarket, you’re probably not thinking about the possibility of being overcharged, but the reality is, it’s happened to most of us. Get into the regular routine of checking your supermarket receipt to make sure that everything adds up, and if it doesn’t, take it up with the retailer in a timely fashion. It’s money that’s better off in your wallet.

Bessie Hassan is a money expert at finder.com.au