Ask HN: Why Do Government Websites Work Human Hours
Here is a perfect example of the IRS deciding servers only work 4am to 7pm pst
https://www.irs.gov/businesses/small-businesses-self-employed/apply-for-an-employer-identification-number-ein-online
https://www.irs.gov/businesses/small-businesses-self-employed/apply-for-an-employer-identification-number-ein-online
For example, they might need several hours in the middle of the night to process the day's transactions through ancient, overloaded mainframe batch-processing systems. Or they might need the nights and weekends to do maintenance (e.g., programming, testing or backups) on the system, which the system is too overloaded to handle while it's available to users.
Not to mention that it's currently not even a month after the tax due date, so right now they'd be prioritizing the use of their systems to process people's tax returns while deprioritizing all other transactions.