About PDF/A:
PDF/A is an archival standard format intended to support long-term archiving of electronic documents. Compliance with the standard guarantees that PDF/A documents can be viewed and reproduced in exactly the same way for years to come, regardless of future changes to PDF format standards.

The Federal Judiciary is planning to change the technical standard for filing documents in the Case Management and Electronic Case Filing (CM/ECF) system from PDF to PDF/A.

Click here to confirm your viewer is PDF/A compatible: https://www.pacer.gov/documents/sample_pdfa.pdf

Follow these steps to convert Microsoft Word Files to PDF/A
Choose the folder
Enter the file name
Choose PDF for document type
Click ‘More Options’ link
Choose ‘Options’ button
Check PDF/A compliant
Click OK

Follow these steps in Acrobat X:
Open a PDF file that you wish to conform to PDF/A
Choose File> Save As> More Options> PDF/A

Follow these steps for Adobe Acrobat DC
Convert to PDF/X, PDF/A, or PDF/E using a profile
Choose Tools > Print Production.
The Print Production toolset is displayed in the right hand pane.
Click Preflight.
The Preflight dialog box is displayed.
In the Preflight dialog box, choose PDF Standards from the Libraries drop-down list.
Click on the Profiles tab.
Expand a compliance profile and select the profile you want. For example, under PDF/A Compliance, select Convert To PDF/A-1b.
Click Analyze And Fix.
Click Save to convert the file based on the selected profile.
Learn more about Adobe Acrobat DC options here: https://helpx.adobe.com/acrobat/using/pdf-x-pdf-a-pdf.html

Most PDF writers will have an option to save as PDF/A.
However, you can use an online converter to change any files into PDF/A compliant, like: