Every time you walk out of a restaurant or cafe, you could be setting yourself up for mandatory 14 days of isolation because of one small mistake.

For those residing in NSW, every time you visit a hospitality venue, you must check in and out using the ServiceNSW app.

Since January 1, the state government has made it mandatory for all businesses to use the ServiceNSW app for contact tracing purposes.

Most venues already had the app in place before the mandate.

However, if you forget to “check out” after you leave, you could land yourself in trouble.

The “check out” feature was added on November 16 2020, to help contact tracers pinpoint the exact movements of active COVID-19 cases.

It means if an active case visits a venue you were at hours after you, but you haven’t “checked out”, you could be made to self-isolate for 14 days.

Roughly two out of three NSW patrons forget to check out.

A spokesperson for the government told 7NEWS they had recorded 9.2 million (checkouts) since November 2020 – which is 35 per cent of people using the app.

That means around 17 million people haven’t checked out.

The spokesperson said “The ‘Check Out’ feature is not mandatory for customers – and businesses don’t need to ask them to do so – but it is strongly encouraged.

“An update to the ‘Check Out’ feature is one of many enhancements in the pipeline for the COVID Safe Check In.”

To check out of a venue, you need to go back into the ServiceNSW app and tick “check out”.

If you have closed the app then you need to navigate back to the home screen, click “COVID Safe Check in” then click “Last Check-in”.

Data on the COVID Safe Check is deleted by the government after 28 days.

This article originally appeared on Over60.