Taxpayers are asked to "do one thing" and download the HMRC app to save time and simplify money and tax management.
This appeal comes as part of Talk Money Week, an annual awareness event taking place from November 4 to November 8.
The theme for this year is "Do One Thing."
Currently, more than 1.7 million people are making use of the app every month.
Between July and September 2024, 711,382 new users downloaded the app.
There was a 39 per cent increase in app activity compared to the same period last year, going up from 20.93 million sessions to 29.22 million.
The app provides access to a variety of services, including a tax calculator to estimate take-home pay, National Insurance number retrieval, and making a Child Benefit claim.
The most popular features, from July to September this year, were checking State Pension contributions, managing Child Benefits, and viewing annual tax summaries, with 1.9 million, 1.6 million, and 1.4 million sessions respectively.
Myrtle Lloyd, HMRC’s director general for customer services, said: "One of the main priorities for HMRC is improving our customer services, and this incredibly useful and user-friendly app is a great example of how tax can be made much easier for people.
"Whether you’re a student looking for your National Insurance number or a new parent wanting to claim Child Benefit, the HMRC app has a range of tools for you, at your fingertips.
"I urge everyone to download it today."
The app is highly rated on both Google Play Store and Apple Store, at 4.7/5 and 4.8/5 respectively, and ranks among the top 10 finance apps on both platforms.
To encourage more people to use the app, HMRC is launching an advertising campaign aimed at 18 to 34-year-olds.
The campaign highlights how the app can help them keep on top of their tax matters and finances amidst their busy daily lives.
The campaign includes a new advert, which is streaming on multiple video-on-demand channels and is also available on the HMRC YouTube channel.
The advert is part of HMRC's aim to 'improve customer service and make tax management easier for everyone.'
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