Have you ever entered a date such as 11/40 in Excel or Microsoft Access, only to have it turn into January 1, 2040? That is especially annoying when you are entering birth dates, genealogy records, cemetery information, or any other historical data where 1940 is a whole lot more likely than 2040. The problem is not that Excel or Access is broken. It is how Windows interprets two-digit years.
A two-digit year is ambiguous by definition. When you type 35, does that mean 1935, 2035, or perhaps 2435 if you are entering dates aboard the Enterprise? Windows has to make an assumption, so it uses something called a two-digit year cutoff. Once you understand that cutoff, you can change it when it makes sense for your work.
With the common current Windows setting, years from 00 through 49 are interpreted as 2000 through 2049. Years from 50 through 99 are interpreted as 1950 through 1999.
So if you enter 11/40, Windows assumes you mean 2040. Enter 11/72, however, and Windows assumes 1972. The computer is not trying to mess with you. It just has to draw the line somewhere, and by default it assumes that lower two-digit years are probably future dates or relatively recent dates.
This is important because it is generally not an Excel setting or an Access setting. Both programs rely on Windows to help interpret dates typed in using two-digit years. That is why the same date entry can behave the same way in Excel, Access, and other Windows-aware applications.
For the average person entering invoice dates, appointments, warranties, due dates, schedules, and other business records, the default behavior makes sense. If someone types 35, they probably mean 2035, not 1935. But if you work in a doctor's office, deal with geriatric patients, maintain historical records, work for a genealogist, or manage a cemetery database, that assumption can be completely backwards.
Fortunately, you can adjust the cutoff in Windows. Open the Control Panel, go to Clock and Region, then select Region. Click Additional Settings, open the Date tab, and look for the setting labeled When a two digit year is entered, interpret a year between.
For example, if you change the cutoff to 2029, then two-digit years from 00 through 29 will be treated as 2000 through 2029. Years from 30 through 99 will be interpreted as 1930 through 1999. After making that change, entering 11/30 will produce a date in 1930 instead of 2030.
That can save a lot of frustration if you regularly enter dates from the 1930s and 1940s. Once the setting is changed, Excel and Access should immediately follow the new Windows interpretation. You do not need to hunt through both programs looking for separate date settings, because there usually are not any to change for this particular behavior.
If you need to change this setting on several computers, there is a handy shortcut. Press Windows-R to open the Run dialog, type intl.cpl, and press Enter. That opens the Region settings directly, saving you a few clicks. It is not something most people need every day, but it is useful if you are setting up a group of workstations for a medical office or historical data-entry project.
There is one big caution: changing the Windows cutoff affects how two-digit years are interpreted across the computer. That may be exactly what you want, but it also means someone entering an appointment date of 11/35 might now get 1935 instead of 2035. Pick a cutoff that makes sense for the type of data your users enter most often.
Personally, the best solution is still to avoid two-digit years whenever possible. Type the full four-digit year. Better yet, use the ISO date format: YYYY-MM-DD. For example, 1940-11-01 is completely unambiguous. It does not depend on a Windows cutoff, it does not depend on regional date formats, and it does not make the computer guess what century you meant.
In an Access application, you can also take this a step further. Rather than changing the Windows setting for every user, an Access developer can create a reusable function that applies a custom cutoff only where it is needed, such as a Date of Birth field. That lets the application control the interpretation without affecting order dates, invoice dates, or other fields that may need a different assumption. The full implementation and demonstration are included in the embedded video.
So if 1940 keeps becoming 2040, now you know why. Windows is applying its two-digit year cutoff, and Excel and Access are following along. Change the cutoff if your work calls for it, but whenever you can, enter all four digits of the year and eliminate the ambiguity entirely.
You can watch the embedded video for the full walkthrough and a live demonstration in both Excel and Microsoft Access.
Live long and prosper,
RR
