How Do I Add Attachments to the 5500?

Start editing the 5500 as outlined in How do I Complete the 5500?.
Click the 'Upload Attachments' link under the "I'm Done" button in the upper left corner of the page.
To upload an attachment, select the attachment type, select your attachment file by clicking the 'Browse...' button, optionally fill in an attachment name, and click the 'Add Attachment' button to upload.

There are limits to the size of a filing that will be accepted by the DOL. In general, scanned attachments should be saved as black and white images. Resolutions of as low as 100 x 100 will typically produce an acceptable image. A resolution of 300 x 300 creates files of approximately 1 MB per page in size. There should not be any filings that need to undergo exception processing due to EFAST2 limitations if attachments are scanned at 300 x 300 or lower resolution.
Once an attachment has been added, it will be listed in the 'Uploaded Attachments' box.
When done, click the 'Return to Edit 5500' button at the bottom of the page to complete the 5500.