Presente de subjuntivo
English barely has a subjunctive ('I wish he were here'); Spanish uses one constantly. Subjuntivo shows up with verbs of wanting, emotion, doubt, after certain conjunctions, and in impersonal expressions. Today: how the forms are built and the three most common contexts.
How it's formed (the 'flip' rule)
Take the yo form of the present (hablo, como, vivo, tengo, hago…). Drop the -o. Add the opposite endings: for -ar verbs: -e, -es, -e, -emos, -éis, -en. For -er and -ir verbs: -a, -as, -a, -amos, -áis, -an. hablar → habl- → hable, hables, hable, hablemos, habléis, hablen. comer → com- → coma, comas, coma, comamos, comáis, coman.
Irregular verbs — start from the yo form
If a verb has a special yo form in the present (tengo, hago, digo, vengo, salgo, conozco), that becomes the subjunctive stem. tener → tenga, tengas… hacer → haga, hagas… decir → diga, digas… Stem-changers (querer → quiero) keep the change: quiera, quieras, quiera, queramos, queráis, quieran.
Six fully irregular ones
ser → sea, seas, sea, seamos, seáis, sean. ir → vaya, vayas, vaya, vayamos, vayáis, vayan. estar → esté, estés, esté, estemos, estéis, estén. dar → dé, des, dé, demos, deis, den. saber → sepa, sepas, sepa, sepamos, sepáis, sepan. haber → haya, hayas, haya, hayamos, hayáis, hayan.
Use #1: wishes / 'want that'
After querer que (to want that), esperar que (to hope that), pedir que (to ask that) — subjuntivo. Quiero que vengas (I want you to come). Espero que estés bien (I hope you're well). Mi mamá pide que limpie la casa (my mom asks me to clean the house). The trigger is two different subjects: I want SOMEONE ELSE to do something.
Use #2: emotions
After me alegro de que (glad that), me gusta que (I like that), es bueno/malo que (it's good/bad that), qué pena que (what a shame that). Me alegro de que estés aquí (I'm glad you're here). Es bueno que estudies (it's good that you study). Qué pena que no puedas venir (too bad you can't come).
Use #3: doubt and negation
After no creo que (I don't think that), no es verdad que (it's not true that), dudo que (I doubt that), es posible que (it's possible that). No creo que vengas (I don't think you'll come). Es posible que llueva (it might rain). Note: creo que (without negation) takes the indicative! Creo que vienes (I think you're coming). Certainty → indicative. Doubt → subjunctive.
Useful templates
Memorize as set phrases: Que tengas un buen día (have a good day — literally 'may you have a good day'). ¡Que duermas bien! (sleep well). Ojalá llueva (I hope it rains / hopefully it rains). These are baked into everyday speech.
