UK Payroll Software and Print Management Software

How can I transmit to the HMRC via a proxy server?

I have a proxy server installed and when I try to transmit to the HMRC, I get a proxy authentication failure.  How do I resolve this

You need to create a file in the same directory as onlinereturns.exe program (this will usually be in the install directory for csmascent payroll).  The file should be named ProxyConfig.xml and should contain the following lines:
<root>
    <Proxy>
        <Name>http://{IP address of your proxy server}:{port number}</Name>
        <UseDefaultCredentials>True</UseDefaultCredentials>
    </Proxy>
</root>
An example would be:
<root>
    <Proxy>
        <Name>http://192.168.1.159:80</Name>
        <UseDefaultCredentials>True</UseDefaultCredentials>
    </Proxy>
</root>
Please note that the filename and file contents are all case-sensitive!
This should allow access.