Treasury/IRS released their shutdown plan stating that normal IRS operations will continue for five business days using Inflation Reduction Act of 2022 ("IRA") funding.  This means that all 74, 299 employees will continue to work through at least Tuesday, October 7, 2025.  The plan says that, if Treasury/IRS does have to shut down, it would take up to half a workday to completely shut down activities.

The shutdown plan does not say what happens if the government is still shut down on October 7.  The IRA provides appropriations through September 30, 2031, so it might be possible for Treasury/IRS to continue to use the IRS funding to remain open past October 7. 

The most recent shutdown lasted for 34 days from December 2018 into January 2019.  

Read the shutdown plan here.