REST API, birthday value shifts

When using REST API, if I create or update a contact and specify “birthday” field, the value stored in IS is one day less. For example using {“birthday”: “2000-01-01”} or {“birthday”: “2000-01-01T00:00:00”} produces 12-29-1999 in IS.

Anyone knows the reason? Are timezones involved?

Thank you.

In admin->settings on the general page, at the bottom you should have a time zone setting. I believe this is what affects it?

Changing that field had no effect and the help for it says that it only affects timers. Why would a birthday even be affected by timezones? Any other ideas?

This one is tricky. I believe what @John_Borelli was going for was the user timezone setting found under Admin → Users → [YourUser] → Preferences.

I would also like to mention that for contacts and a couple reports the date format is changed based off of browser settings which it doesn’t sound like is the issue here however I would like to add it just in case someone looks at this post in the future and needs to know this information. To change it here is a link that might help: