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By David Ringstrom, CPA
Many users rely on the NOW() function to return today's date in a spreadsheet. This is a perfectly valid purpose, but in certain cases NOW() can cause a formula headache.
The NOW() function returns both today's date, but also the current time as well. For instance, if it's 12:00 p.m. on December 21, 2012, the formula =NOW() in a worksheet cell will return 41,264.50. This is because 12/21/12 is 41,264 days subsequent to January 1, 1900.
The .50 portion represents half of a twenty-four-hour day. Thus, if you're comparing a static date value, such as 12/21/12 to the NOW() function, Excel will indicate that they don't match, because 41,264 isn't equal to 41,264.50.
The solution for comparing dates is to use the TODAY() function instead, since it returns the date portion only; for example, 41,264 for 12/21/12.