If you have already submitted your application and then your startup has material changes to the idea, new cofounders, huge progress, etc. you can email us usin

If you have already submitted your application and then your startup has material changes to the idea, new cofounders, huge progress, etc. you can email us using this form https://www.ycombinator.com/contact/ https://www.ycombinator.com/contact/ and we will make sure to make note of what has changed since you submitted.