I do not know anything about caja fees except for what I have read here. Googling caja fee for a chart led me to this site.
https://www.crie.cr/en/caja-fees-increase/ This site explains the caja has two parts 1) SEM - healthcare coverage, and 2) IVM - pension contributions. The contribution to IVM/pension seems to be new and the site explains those with caja prior to March 2022 do not have to pay into the IVM/pension, and could opt out. Now it seems mandatory. It was unclear to me what happens when one needs to renew their temporary residency, will the new rate apply or are they grandfathered in and do not need to pay the IVM/pension.
The cost for $2,500 rentestia temporary residency based on the chart says it costs 8.2% for the SEM/healthcare, and 7.65% for the IVM/pension. So (2,500 x 8.2%) + (2,500 x 7.65%) = $396.25 USD monthly Caja payment.
The $400 seems to agree with something I found on the internet. Not sure what others are paying. If you search the forum, others have talked about caja costs, residency and other issues.
The costa rica star news paper has an article addressing the same issue.
https://news.co.cr/caja-rates-spikes-fo ... ica/82984/ I could not find a chart on the official ccss website, but they did have a calculator. However, it seems like it is not available on the website anymore. May be do to the recent hacking that took place.