The T10 and T11 are file extensions used by tax preparation software called At Home. You are able to view content of these files in the software, but there is actually no need to convert them, because they appear to be in the same file format, only with different file extension that indicates year of tax return.
Convert At Home 2010 tax return form to At Home 2011 tax return file.
We found 2 software records in the database related to .t10 to .t11 file format conversion.
Microsoft Windows software - convert t10 to t11 on Windows
A popular tax preparation software from HRB Digital
Convert from t10 file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned t10 to t11. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
Apple macOS / Mac OS X software - convert t10 to t11 on OS X
A complete a simple federal tax return software