As três escadas do se
Portuguese conditional sentences come in three flavors, and each has a strict pairing of tenses. Real (it might actually happen): se + present indicativo, then present or future. Hypothetical (if I were…): se + imperfeito do conjuntivo, then condicional or imperfeito do indicativo. Counterfactual (if I had…, but I didn't): se + mais-que-perfeito do conjuntivo, then condicional composto. Once you know which rung you're on, the verbs lock in.
Rung 1 — real conditions: se + presente do indicativo
When the se clause describes something that genuinely might happen, use the present indicative — never the conjuntivo, even though English uses 'if'. The main clause is present or future indicative. Se chove, fico em casa = If it rains, I stay home. Se tens tempo, vais ao mercado? = If you have time, will you go to the market? Se eles vierem cedo, jantamos juntos — wait: when se points to a future event, Portuguese uses the futuro do conjuntivo (a separate tense for quando, se, assim que etc. with future reference): se vierem (when they come), se puder (when I can). For now, treat se + present as the safe everyday version, and recognize se vier, se puder, se tiver as future-leaning variants you'll meet in B2.
Rung 2 — hypothetical: se + imperfeito do conjuntivo
For unreal-but-imaginable situations ('if I had time', 'if I were rich'), use the imperfeito do conjuntivo in the se clause and the condicional in the main clause. The imperfeito do conjuntivo is built from the 3rd plural pretérito perfeito stem (the eles form minus -ram) plus -sse, -sses, -sse, -ssemos, -sseis, -ssem. falaram → fala- → falasse, falasses, falasse, falássemos, falásseis, falassem. comeram → come- → comesse. partiram → parti- → partisse. Irregulars carry over: foram → fosse, tiveram → tivesse, fizeram → fizesse, disseram → dissesse, puderam → pudesse, soubessem from souberam. Se tivesse tempo, iria contigo = If I had time, I'd go with you. Se fosse rico, comprava uma casa (the indicative imperfeito comprava is a colloquial swap for the condicional compraria — both are heard).
Rung 3 — counterfactual: se + mais-que-perfeito do conjuntivo
For things that DIDN'T happen and we wish had (or fear had), use se + tivesse / houvesse + past participle, then condicional composto (lesson 29's territory) or, more colloquially, the imperfeito do indicativo + past participle (tinha + part.). Se tivesse estudado mais, teria passado = If I had studied more, I would have passed. Se tivessem chegado a tempo, não teriam perdido o comboio = If they had arrived on time, they wouldn't have missed the train. The auxiliary is ter in the imperfeito do conjuntivo (tivesse, tivesses, tivesse, tivéssemos, tivésseis, tivessem) — haver is reserved for very formal writing. The past participle (estudado, falado, comido, partido) is invariable in this construction.
Mixing the rungs — and what NOT to mix
Standard PT keeps the pairings tight: se + presente → presente/futuro indicativo; se + imperfeito conjuntivo → condicional / imperfeito indicativo; se + mais-que-perfeito conjuntivo → condicional composto / mais-que-perfeito indicativo composto. Crucially, se in conditional sentences NEVER takes the present conjuntivo — that's a common learner mistake. Se ele venha is wrong; it's se ele vem (real) or se ele viesse (hypothetical). For 'maybe', use talvez + conjuntivo, NOT se + conjuntivo. Mixing rungs across clauses is grammatically possible but stylistically marked: Se tivesse estudado, passaria amanhã (had + would future) is rare and usually rewritten.
Brazilian register: speech crowds out writing
BR colloquial speech freely substitutes the imperfeito do indicativo for the condicional in rung 2: se eu tivesse tempo, eu ia (instead of iria). PT does this too. In rung 3, BR speech often goes a step further and uses the imperfeito do indicativo on BOTH sides: se eu tivesse estudado, eu passava — clearly counterfactual but lexically simpler. Both PT and BR also drop se + future conjuntivo into the present indicativo in casual speech: se você puder → se você poder (technically wrong but heard). For writing, stay with the textbook pairings.
