All about TAX Files

The TAX file type is primarily associated with TaxACT.

TAX	File extension: TAX
	File type:	data file

What is a TAX file?

TAX files mostly belong to TaxACT. TAX files hold structured tax return data used by specialized tax software to process income tax filings.
This format is not for general text editing; it stores numeric and form-based data and often uses internal structures like XML or ZIP compression to organize the information. The file is designed to be imported into dedicated programs that help calculate and file tax returns.
Key Use Cases:

US Tax Returns: Files created by systems such as TaxACT and TurboTax hold federal and state tax details.

Indian Income Tax Returns: Files from products like Tally ERP store income details and other necessary data for Indian tax filings (Tally Solutions).

Canadian tax files, often in XML format, are linked to agencies like the Canada Revenue Agency.

German tax data files managed by companies such as DATEV (compatible with ElsterFormular) organize tax information (DATEV).

Swiss tax return files sometimes use a compressed ZIP format and are maintained by providers like DVBern (DVBern).

FilExt.com note: These files should be opened using the corresponding tax software to ensure data is processed correctly.

How to open a TAX file

You need a suitable software like TaxACT to open a TAX file. Without proper software you will receive a Windows message "How do you want to open this file?" or "Windows cannot open this file" or a similar Mac/iPhone/Android alert. If you cannot open your TAX file correctly, try to right-click or long-press the file. Then click "Open with" and choose an application. You can also display a TAX file directly in the browser:. Just drag the file onto this browser window and drop it.

Online TAX Text Viewer

Choose your .tax file to analyze

or drag and drop it here

Online File Viewer

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TAX file format:

If you know the file format, you can also find out how to open or edit the file. Often, the file format can be deduced from the file extension or the initial bytes (called the signature). However, different programs can use the same file extension. Furthermore, a file extension can be renamed incorrectly and double-clicking on it will then display an error when it is opened. So a detailed analysis of a file is vital in order to determine the format and the associated program. Our evaluation of the TAX files looks like this:

TAX is not a common file extension and covers different formats for different programs. The two most common formats are as follows:

• 35% of all TAX files use the same file format, which have the signature C0 45. If you open these files in a text editor, you can view the contents and find segments of text. The file size is in the range of 120 KB to 580 KB. This file type was primarily in use more than 20 years ago. Files like these are about return, turbo, recovered and loan, and often include person-related information.
• 15% of all TAX files use the same file format, which can be identified by the letters "11 00 57 37 21 59 31 36 42 21 7D 2A 2B 2C 2B 2A" at the beginning. The contents of these files are easily readable with a text editor. TAX files can be up to 1 MB in size, but are often around 360 KB - 980 KB. The files contain the following words: W7!Y16B!}*+,+*<%\, abB8("+*(}' and 4;+-+}%\. Such TAX files store data about person-related data.

All other TAX files (50%) have different formats, the following 5 formats can be found: TurboTax return, XML and ZIP. Just click the "Choose your .tax file to analyze" button on this page to find out what your TAX file is.