It's too soon to answer that question definitively, but it's not too soon for investors to take some defensive action.

If it does happen, it'll be different from those that have gone before. Let's break it all down…

While most of us keep our books and records on a Dec. 31 fiscal year, the U.S. government is different. The U.S. fiscal year runs from Oct. 1 until midnight on Sept. 30.

The fiscal year is dated by the calendar year in which the last day falls.

So the fiscal year beginning on Oct. 1, 2023, is called "Fiscal Year 2024" by the Government Accounting Office (GAO) and the Office of Management and Budget (OMB). Leave it to the government to make things difficult and hard to follow, but that's how they do it.

That means fiscal year 2023 ends at midnight on Sept. 30, 2023. We're up against the clock and that's why you're hearing so much about a government shutdown right now.

It's the job of Congress to pass appropriations bills to keep the government open. Under so-called regular order, each major department has its own appropriations bill. So there should be separate bills for Defense, the State Department, the Department of Education and so on.

Each bill should be voted on separately and each bill should pass before Sept. 30 to keep that department and the government as a whole running in the new fiscal year.

But in the real world, the "regular order" process never happens. Typically, the House and Senate and the two parties in each body can't agree on anything by Sept. 30.