What is the timezone used to compute the 90-day early filing date?

Question

https://www.uscis.gov/forms/uscis-early-filing-calculator mentions:

You may file Form N-400, Application for Naturalization, 90 calendar days before you complete your permanent residence requirement if your eligibility for naturalization is based upon being a:

• Permanent resident for at least 5 years; or

• Permanent resident for at least 3 years if you are married to a US citizen.

What is the timezone used to compute the 90-day early filing date? E.g., does submitting the N-400 on May 2, 2022 1 AM PT count as filing on May 1 or May 2?

Answer 1

In an answer to a similar question here, USCIS refers to UTC as the controlling time.

Q9. How are date and time recognized by the system? Does the applicant’s time zone control? For example, will an applicant on the U.S. west coast attempting to file at the last minute discover that the filing window has closed because the system recognizes eastern time?

A9. The system recognizes UTC or Coordinated Universal Time.

Whether you want to rely on that or maybe wait till the morning of the right day to file and not risk weeks of waiting for rejection and extra filing fee to refile - is up to you.