With the end-of-financial year upon us, a lot of people will be getting to know their accountants a whole lot better again. Whether it is for your personal tax return, or for a corporate set of books, it has now become common to email your accountant certain files.

Most accounting files – whether they're in Excel files, from MYOB or a larger system – are mostly text, and they can be shrunk by a process known as 'zipping' to make them easier to email. While this has performance benefits, there is another little-known feature of zip files that can make this highly sensitive data all the more secure.

Zip files aren't new, and there's a good chance you've used them more than a couple of times in your computing experience. Technically, a zip file is a type of file that contains at least one, and potentially thousands, of other files within it, all compressed. By following a standard formula – known as an algorithm – zip file can often be one tenth the size, or even less, of the source files they contain.

One of the other handy, and less well known, features of the zip file format is its ability to be password protected. While not the strongest protection available in the world, this is a simple and effective way to keep prying eyes out of your information; particularly handy at this time of year with the amount of financial data being shared among accounting professionals.

To password protect a file in WinZip, the leading Zip application on the market, is simple.

1. Download and install WinZip from www.winzip.com. This program is shareware, and while it will work after it expires, you probably should pay the small licence cost and get rid of the 'nag screen' that comes up every time you run the evaluation version.

2. Select the files you want to zip from Windows Explorer. You can select multiple files by dragging your mouse over them, or by holding down the control key. Folders can also be added to zip files.

3. Right click, and choose "Add to Zip File…". This will then launch the WinZip program.

4. Choose the destination location for the zip file in the top area. This will be where the zip file is saved to.

5. Before hitting "Add", click on the checkbox on the right hand side, "Encrypt added files".

6. Enter a password for the archive. If you're planning on corresponding with your accountant regularly, agree on a password to use so that they'll be able to open the files you send them – and vice versa – without needing to keep telling each other what the password is over the phone. When choosing your encryption method, consult the help system, and if in doubt, choose the 'portable' option.

7. Now click on OK, and you’ll have a compressed, password protected zip file which you can email, or store on the backup server at the office without fear.