The reason for the government shutdown in September 2025 is a failure of Democrats and Republicans in the U.S. Congress to reach an agreement on a crucial short-term funding bill for the federal government. This deadlock is largely due to disputes over healthcare policy, as Democrats want to extend healthcare tax credits and reverse Medicaid cuts, which Republicans oppose. Additionally, there are disagreements over budget reductions for agencies like the Centers for Disease Control and Prevention (CDC) and the National Institutes of Health (NIH). The impasse is intensified by the Trump administration's stance, which has shown willingness to allow a shutdown and reduce the size of the federal government further, including potential permanent job losses for some federal workers. The Senate requires 60 votes to pass funding legislation, but Republicans, although holding a majority, do not have enough votes, giving Democrats leverage in the negotiation. This standoff has led to the imminent shutdown that is set to begin at midnight if no deal is reached.

Key reasons include:

• Lack of agreement on federal government funding for the new fiscal year starting October 1, 2025.
• Disagreements primarily around healthcare subsidies and Medicaid funding.
• Budget cuts proposed by the Trump administration for several health-related agencies.
• Senate voting rules requiring supermajority support, which is not met due to partisan divisions.
• The Trump administration's readiness to potentially use the shutdown to reduce federal workforce size.

This government shutdown would be the first in nearly seven years and could disrupt many federal services and furlough many government workers, though certain critical services would continue.