The present perfect subjunctive is used to express uncertainty, desire, possibility that something happened in the past. The verb in the indicative clause is in the present.
Credo che lui sia partito. / I think (now) that he has gone away (in the past).
Mi sembra che non abbiano pulito la casa. / It seems to me that they haven't cleaned the house.
Sono contento che siano andati via. / I'm happy that they've gone.
Look at the difference between the present perfect subjunctive and the present subjunctive:
Present Subjunctive: Penso che vivesse qui. / I think he lives here.
Present Perfect Subjunctive: Penso che abbia vissuto qui. / I think he lived here.
Look at the difference between the present perfect subjunctive and the present perfect indicative:
Present Perfect Indicative: Lui ha voluto giocare a calcio. / He wanted to play football.
Present Perfect Subjunctive: Credo che lui abbia voluto giocare a calcio.
/ I think he wanted to play football.
We use it with the same verbs as we use the present subjunctive, namely verbs of emotion.
To form the present perfect subjunctive, we use the present subjunctive form of the auxiliary verb essere or avere plus the past participle of the verb.
che io avessi cantato
che tu avessi cantato
che lui/lei avesse cantato
che noi avessimo cantato
che voi aveste cantato
che loro avessimo cantato
che io sia partito/a
che tu sia partito/a
che lui/lei sia partito/a
che noi siamo partiti/e
che voi siate partiti/e
che loro siano partiti/e
Italian Course: Unit 21 The present subjunctive tense
Italian Course: Unit 23 The imperfect subjunctive tense
Italian Course: Unit 25 The pluperfect subjunctive
Italian Course: Unit 28 The present perfect subjunctive tense
Italian Verb Tenses Exercises Imperfect subjunctive, Past subjunctive, ...