The IRS website has a bunch of Interactive Tax Assistants. They're basically a Q&A thing with tax questions like "do I have to file taxes this year?", "can I get an education credit?" and "can I claim moving expenses?". The system will ask you a bunch of questions and then give you an answer. They are very helpful.
Let me use "when are my taxes due?" as an example. For almost everyone, taxes are due on April 18th this year. It's normally April 15th, but this year, it's delayed due to a weekend and a holiday.
There are extenuating circumstances that can change your due date, like if you were in a military combat zone or if you were in a Presidentially-declared disaster area. My personal favorite is if your calendar year doesn't end in December. There are some finance people--called "fiscal year filers"--who have different calendars, due to the nature of their business. I had no idea that was the case!
So in order to be 100% accurate about your due date, the Interactive Tax Assistant has to check to make sure you don't fall under the extenuating circumstances. I know some people just want to hear the general due date and be done with it, but this is definitely a case where you want accuracy over speed.