The IRS has replaced IRS2Go, which had been around since 2011, with a new app simply called “IRS.” The new app is designed to bring selected IRS Individual Online Account functions onto your phone rather than being primarily a refund-status app.
You can now use the app to:
Check your IRS account balance
Make federal tax payments
Review payment history
Check refund and amended-return status
View certain IRS notices and letters
Access available tax records and transcripts
Retrieve your Identity Protection PIN (IP PIN)
Manage certain profile and communication preferences
The app does not replace IRS.gov or Tax Pro Account.
The IRS says the new mobile app initially provides selected Individual Online Account capabilities. It does not provide the full functionality available through:
Individual Online Account
Business Tax Account
Tax Pro Account
Those remain accessible through IRS.gov.
So, for example, if you're working with a client's authorization, POA/TIA, or other practitioner functions, you'll still want Tax Pro Account on IRS.gov rather than expecting the mobile app to handle everything.
If you already had IRS2Go installed, you generally don't have to do anything. With automatic app updates enabled, the IRS says the new IRS app will arrive through the normal update process.
If you download it yourself, be careful to use the official IRS links/app-store listing. The IRS specifically warned about look-alike apps and unsolicited messages pretending to provide IRS account access.
This is essentially IRS2Go evolving from a simple taxpayer utility into a mobile front end for selected IRS Online Account functions. For someone who deals with tax matters regularly, the ability to pull up balances, notices, transcripts and payment information from an iPhone is probably the biggest practical improvement.