Announcement: Update to QPP Submissions API Rate Limit Policy + Recommendations for API Integrators

[Developer Group for QPP APIs]

To prepare for the influx of submissions that CMS expects in the second half of the Year 1 reporting window, CMS is updating the rate limit of the QPP Submissions API to an average threshold of 25 rps (over 2 minute period) and a burst threshold of 40 rps (over 5 second period). 

While CMS is actively working on identifying and addressing bottlenecks within the QPP system that are impacting API performance, we recommend that you proactively modify your queuing processes to the API to minimize the probability of your encountering these known performance issues.

Specific recommendations:

• Spread your requests over a longer period of time. We recommend not exceeding 15 requests per second.
  
• If you exceed the rate limit, you will receive a 403 Access Denied response, and your IP address will be blocked for 10 minutes. However, this 10-minute block is applied after you've terminated your excessive activity. So if you exceed the rate limit, you should cease your excessive activity for at least 10 minutes - otherwise, you will continue to receive 403s from the API.
  
• If your requests start to time-out, implement exponential backoff so that you do not continue to encounter timeouts (resource: https://cloud.google.com/storage/docs/exponential-backoff)
  
• Use a connection timeout of 10 seconds - meaning, your client should abandon a request if it doesn't connect within 10 seconds
  
• Use a maximum timeout of 60 seconds - meaning, your client should wait a maximum of 60 seconds for a response to be served by the QPP Submissions API.
  
• If you are running regular batch jobs, choose a time that is not exactly on the hour, so that the system is not overloaded with users who have all chose to run hourly on the hour.
  

This updated rate limit policy and CMS' recommendations will help you avoid the QPP Submission API's performance bottlenecks and ensure that your submissions for QPP Year 1 go through smoothly.

We appreciate your continued support of the QPP Developer Tools, and your partnership with CMS.