Hi ​@Nao Kondo, Thanks for asking about this.

That "Dev seat adjustment" fee is a one-time charge, basically a prorated amount. When you adjusting seats, they get added to your next bill, and the charge is prorated from the day you adjusted them.

For the full scoop, please check out the “Prorated billing" part of the Updates to Figma's pricing, seats, and billing experience article.
You can pick your plan there to see how the prorated billing works for you.

Thanks again!

I have the same problem, the only difference is that I need to pay for an extra $15.

​@Junko3 your explanation doesn’t make any sense. Care to give more details?

I my case, I downgraded a full seat to a dev seat last month and now I need to pay extra $15 for that adjustment? How does this work???

​@Junko3 It doesn’t make sense that we’re being charged just for updating seats. I was confused at first, so I made several changes — now it looks like we’ll be charged significantly for that? Could you please clarify why?