30% ruling from USA: proof of deregistration

Hi everyone,
I recently moved to Amsterdam from the US. I qualify for the 30% ruling, but I'm confused by question 1c on the form. It asks if I've lived outside of the Netherlands for more than 16 of the past 24 months, which I have. But, it requests "certificates of registration and deregistration from the population register of this place of residence, or another certificate showing that the employee meets this condition."

Given there's no population registry in the US, I have no idea what I would provide for this. A letter from my previous employer stating the time period I worked on-site there? I assume others have run into this same problem, any suggestions?

We had the same problem moving from the UK; in the end, we asked our local council in the UK to write us a letter saying that we had previously paid our local taxes there, and had ceased paying on whatever date; they accepted that.

I am interested in this question too. Hope someone can give a general answer.

The population register seems to be a thing peculiar to mainland Europe; we didn't have the system in the UK.  They're just looking for some kind of State evidence of who you are and where you lived before you came to Holland; so you have a passport, do you have anything else written by Local/National government with your name on it and the address you've told them you came from.  How about the US State tax system; does that issue anything with your name and address on?  There are plenty of Americans in Holland, so there must be some kind of thing they have provided.

Did you manage to deal with this?
I have the same problem