Paying out of one's own pocket; covering expenses oneself rather than having them paid by others or an organization.
飲み会の費用は今回は自腹で払います。
I'll pay for the party out of my own pocket this time.
彼は新しいパソコンを自腹を切って買った。
He paid for the new computer out of his own pocket.
会社の規定で出張費は原則として自腹で立て替える必要はない。
Under company policy, in principle you don't need to cover travel expenses out of pocket.