This font is available in the libwine package (jessie and earlier) or the fonts-wine package (stretch/jessie-backports and later). Both of these include all the free replacements for common Windows fonts. fonts-wine includes only the fonts, but libwine includes other files for Wine.
Obtaining the Microsoft Tahoma font
Purchase a license
A license for the Tahoma font package can be purchased.
You may already have a license to use the Tahoma font if you have a license to a qualifying Microsoft product (i.e. most versions of Windows and Office). Please refer to the terms of the EULA for that product.
If you are willing to be bound by a Microsoft End User License Agreement (or such things are not legally enforceable in your jurisdiction), there are several ways to get the font on your Debian PC.
Download from Microsoft
Update: As at April 2020 the FTP server appears not to be responding.
An archive of ftp.microsoft.com is available at Archive.org.
The specific file referenced below can be found as TAHOMA32.EXE
Tahoma is available from the Microsoft FTP server. The file can be downloaded, extracted, and copied into the appropriate place:
cd /tmp wget ftp://ftp.microsoft.com/Softlib/MSLFILES/tahoma32.exe sudo apt install cabextract || echo "You need 'contrib' in /etc/apt/sources.list" cabextract tahoma32.exe mkdir -p ~/.fonts/ mv Tahoma*.TTF ~/.fonts/
Copy from Windows installation
The file tahoma.ttf can be found in the fonts folder on most Windows PCs. It can be transferred to the ~/.fonts/ directory.
Also see Fonts for general Debian font configuration information.