Get your taxes done using TurboTax

Thank you very much everyone. The problem indeed has to do with regional settings and I have now resolved it on my end by fiddling with the regional settings on my PC. However, it seems to me that we share/shared a common misconception. So, allow me to clarify.

Indeed, I live in Europe, but my PC keyboard/language settings all are US English. Like @rjs I also had the impression that "TurboTax is strictly a U.S. tax program." in the sense that it would parse and interpret and display numbers, currency, dates, etc., according to the US standard format. (Why should it not? Who other than a US taxpayer would ever have any reason to use this software?) If this were actually the case, though, Turbotax would parse, interpret, and display numbers all according to the US standard format, come hell or high water. This means that if a Martian were to run TurboTax on her PC with Martian regional setting, according to which "/" is the decimal separator and ":" is the digit grouping separator, then Turbotax would still parse "10.58" exactly the same way as it would on a US PC, and would also display that value as "10.58" exactly as it would on a US PC. However, this is NOT what Turbotax does! Please bear with me ...

There are only two justifiable, consistent alternatives for the I/O behavior of a software: (1) the software picks a particular I/O formatting standard (say US) and hard-wires it in its code to abide by it throughout, disregarding the regional settings of the OS; or (2) the software chooses not to have an internally hard-wired I/O formatting standard and instead abides by the formatting standard selected by the regional settings of the OS.

As far as I know, up to a few years ago, Turbotax seemed to behave according to the first alternative. Its recent versions, including the 2020 version, do not behave according to EITHER alternative. We have now "discovered" that Turbotax parses and interprets its input according to the formatting standard selected in the regional settings of the OS, but displays numbers according to the US standards. I know there is a good/excellent reason for Turbotax to use the US standard in its output (see below). Nevertheless regardless of that or any other reason, this I/O behavior (using two potentially different standards for input and output) is inconsistent.

Older versions of Turbotax, as I mentioned, serve as examples of software that consistently behave according to the first alternative, mentioned above (all consistent and well). Other software, e.g., for form filling in Adobe Acrobat, behave consistently according to the second alternative, above. What this means is that if Windows ever offered a Martian regional settings, then Adobe Acrobat running on a PC with Martian regional settings would interpret a "1:357/26" typed entry as the numeric value we would represent as "1,357.26" in the US format; would actually display this numeric value as "1:357/26" which is so intuitively familiar to a Martian; and would bark at anyone who ever typed such gibberish as "1,357.26" which cannot be interpreted as a valid Martian-formatted number.

More to the point, if Turbotax chooses to parse its input numbers according to the regional settings of the OS, then to be consistent (alternative 2, above) it must also display its output numbers according to the same regional settings of the OS. This means that on a PC with regional settings that use "," as decimal separator and "." as digit grouping separator, Turbotax must:

(a) bark at you if you type "10.58" because the digit grouping separator must separate groups of 3 digits (Adobe correctly barks at you);

(b) display the numeric value "ten thousand five hundred eighty two" of the typed input "10.582,00" exactly as "10.582,00" (i.e., not "10,582.00"); and

(c) if for any reason it fails to bark and accepts "10.58" as legitimate input representing the numeric value "ten thousand five hundred eighty" then it must display it as "10.580,00" (i.e., not "10,580.00").

But here's the rub: The sole purpose of Turbotax is to produce forms according to the standards set by the IRS and other tax authorities in the US. Obviously, the IRS would not be pleased to see "10.582,64" (not to speak of "10:582/64") in lieu of "10,582.64" anywhere in its forms. Therefore, the output format of Turbotax must abide by the US standard, even if that output is produced by Turbotax running on a PC with Martian regional settings. What this means, therefore, is that in order to be consistent, Turbotax must NEVER subordinate how it interprets its numeric input to the regional settings of the OS, and instead ALWAYS parse and interpret its input according to the US standard format. Turbotax used to behave that way up until a few years ago. As we see, it no longer does.

I maintain that this (potentially inconsistent I/O behavior) is a (design) bug in Turbotax. I say so because there is no justifiable reason for Turbotax to ever treat its input according to anything other than the US format (regardless of the regional settings of the OS), given that its output format must always be according to the US format. You never encounter this inconsistency bug as long as your OS regional settings happens to be consistent with the US format.

For the sake of completeness, if you do not live in the US (and there are quite a few expats out there) it is not a good idea to just change your PC's regional settings to US wholesale, because that may affect your date, time zone, etc., and mess things up on your PC.  Windows allows you to fine-tune your settings. 

Here is what you need to do to make your regional settings compatible with the US number format (this may still cause problems with your other applications, such as form filling in Adobe Acrobat), so you may want to reset these settings back to your local settings once you're done running Turbotax (at least until Turbotax fixes this bug in a future version, if ever).

Go to the Time & Language part of your PC Settings:

Next click on "Date, time & regional formatting" link on the right edge of the above window to see something like:

Now click on the "Additional date, time & regional settings" link on the right edge of the above window.  A new window opens:

Under Region in the above window, click on "Change date, time, or number formats" to open a new window as the following:

Now in the above window, click on the "Additional settings ..." button to open yet another window like the following:

In the above window, make sure you select "." as the "Decimal symbol:" and "," as the "Digit grouping symbol:"  Then click on the "Apply" button, and then click on the "OK" button to close the window.