Hey, can you give an example of how the date property will updated monthly? 

According to this help article,

“Klaviyo will check if someone qualifies for a flow whenever a date is added or updated on a profile.”

Be mindful if it’s a flow that lasts over a period of time to understand how Klaviyo handles those scenarios (they could be kicked out of the flow):

Before every action in a flow (e.g., before every email or SMS that goes out), Klaviyo verifies that the date used to trigger the flow is still the same. This means that if someone is in a date-based flow but changes the date such that it falls outside the flow’s timeline, they will not be sent any further messages.

Hello, 

The date itself is a deadline set to the end of the month – then, on the first of the next month or essentially once this deadline has passed, the date updates again to the end of the now current month. 

I guess there’s two concerns –

Regarding a general monthly repeating flow, it sounds like we don’t need to set it to repeat since the date does update and the actions in the flow precede the deadline. 

However, a second concern now is that we do have one flow that is set to send on the 1st of each month, or the day after the deadline. We couldn’t find a way to configure this, so we set a date trigger of the deadline, and then wait 1 day and send an email then. However, since the deadline will have updated by the time we want the email to go out, I presume it would fall under the second warning you mentioned:
“Before every action in a flow (e.g., before every email or SMS that goes out), Klaviyo verifies that the date used to trigger the flow is still the same.”

If this is the case, is there any kind of workaround to have a flow set to a specific date of the month regardless of when the date property is?

Hmmm, my head is spinning thinking about all the dates!

How about this.. would sending a campaign work instead? Queue up 12 campaigns for the year and let it run on a segment that's determined at the time of send?