noun
initiation fee; admission fee; membership fee
A one-time fee paid when joining an organization, club, gym, or school. Often non-refundable and separate from monthly dues.
このジムは入会金が無料です。
This gym has no initiation fee.
入会金はおいくらですか。
How much is the admission fee?
年会費 is an annual membership fee, often for credit cards or clubs, distinct from the initial 入会金.
Compound of 入会 (にゅうかい, 'joining') and 金 (きん, 'money').