The subjunctive is not used very often in English, but is is very common and important in Spanish. Some command forms are actually the subjunctive, so the formation of the present subjunctive should not be too difficult.

Present Subjunctive

-ar verbs		-er and -ir
-e -es -e	-emos -éis -en	-a -as -a	-amos -áis -an

The past subjunctive is formed from the third person plural of the preterite. Remove the -on ending, and add these new endings:

Past Subjunctive

all verbs
-a -as -a	-amos -ais -an

An accent is added to the stem vowel as well in the first person plural form. Instead of hablaramos, it is habláramos; instead of comieramos, it is comiéramos, etc. Note that there is another way to form the past subjunctive (a different set of endings), but the endings given are used more often.

The present perfect subjunctive is formed with the present subjunctive of haber and the past participle of the main verb. Similarly, the past perfect subjunctive is formed with the past subjunctive of haber and the past participle of the main verb.

Present perfect subjunctive				Past perfect subjunctive
haya hayas haya	hayamos hayáis hayan	+ past participle		hubiera hubieras hubiera	hubiéramos hubierais hubieran	+ past participle