There are various causes for paper skew.
Please check the following points to avoid the skew:

Set the document correctly (only applicable for Copy or fax)
Please make sure you set the document in the ADF (Automatic Document Feeder) and adjust the paper guides to fit the width of your documents or on the scanner glass without a skew.

Load the paper correctly in the paper tray
Please make sure you load the paper in the paper tray correctly. Adjust the paper guides to fit the width of the paper you are using.

Check the paper specification
Please make sure you are using the paper which meets the required specification. For details, please refer to the User's Guide. The latest User's Guide is available in the Manuals section.

Check the paper size setting of the printer driver
Please make sure the correct paper size is selected in the printer driver to match the paper you are using.

NOTE:The steps may differ depending on the operating system being used.

1. Cilck Start => Settings => Printers and Faxes=> Right click on the printer icon for your machine and select Printer Preferences.
2. Click Basic tab and check the setting  for Paper Size.

Clean the paper feed rollers or pads
Click here to see the Related FAQs for the details of cleaning.