Exclusive: Today I learned that Excel incorrectly assumes 1900 was a leap year, and Microsoft will never fix it because the whole house of cards would collapse

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Subscribe to our newsletter Nestled away amongst a pile of recently updated pages on Microsoft's Learn site, which contains product documentation and technical resources, was a curiously titled article: "Excel incorrectly assumes that the year 1900 is a leap year." I thought that can't be right, surely everything would have fallen over long ago, but it turns out that this problem has long been known about among Excel-fanciers and Microsoft is never going to fix it: because then everything would collapse."When Lotus 1-2-3 was first released, the program assumed that the year 1900 was a leap year, even though it actually was not a leap year," reads the Microsoft explanation.

"This made it easier for the program to handle leap years and caused no harm to almost all date calculations in Lotus 1-2-3."Lotus 1-2-3 was the Excel before Excel, a hugely popular spreadsheet program by Lotus Software that helped IBM PCs break into and dominate the 1980s business market ## Editor's Note The implications of this news could be significant for the industry. Source: [PC Gamer](https://www.pcgamer.com/gaming-industry/today-i-learned-that-excel-incorrectly-assumes-1900-was-a-leap-year-and-microsoft-will-never-fix-it-because-the-whole-house-of-cards-would-collapse/)