What is tense backshift in Spanish reported speech?

When you report what someone said and the reporting verb is in the past (dijo que, comentó que, explicó que), the tense of the original words moves back one step. The present becomes the imperfect (estoy to dijo que estaba), the preterite and perfect become the pluperfect (llegué to dijo que había llegado), and the future becomes the conditional (vendré to dijo que vendría). The imperfect and the conditional are already as far back as they go, so they do not change. The present subjunctive becomes the imperfect subjunctive.

Does Spanish always need que after the reporting verb?

Yes. Where English freely drops the conjunction - he said he was tired - Spanish keeps que every time: dijo que estaba cansado, never dijo estaba cansado. The que is obligatory after decir, comentar, explicar, contestar and the rest of the reporting verbs. Leaving it out is one of the most common English-speaker errors in reported speech, and it makes the sentence ungrammatical rather than merely informal.

When does the backshift not happen?

When the reporting verb is in the present (or future). Dice que, dice, comenta que all report in the here-and-now, so the original tense stays exactly as spoken: dice que está cansado, not dice que estaba cansado. The backshift is triggered only by a past reporting verb. So the same original words - estoy cansado - give dice que está cansado with a present reporting verb but dijo que estaba cansado with a past one.

Reported Speech in Spanish: tense backshift

There are two ways to pass on what somebody said. You can quote them - "Estoy cansado" - which is direct speech. Or you can report them, threading the words through a verb like decir: Dijo que estaba cansado. That is indirect, or reported, speech, and the move that makes it work is the backshift.

The whole topic rests on one observation: when the reporting verb sits in the past, the tense of what was said slides back one step. Get that table straight and reported speech is mechanical. This page assumes you can already build the imperfect, the pluperfect, the conditional and the imperfect subjunctive; reported speech does not invent new tenses, it just selects among the ones you have.

The one rule: past reporting verb triggers the backshift

If the reporting verb is dijo, comentó, explicó, contestó - anything past - the original tense moves back. Here is the full table.

Present -> imperfect. "Estoy cansado" -> Dijo que estaba cansado. (He said he was tired.)
Preterite -> pluperfect. "Llegué tarde" -> Dijo que había llegado tarde. (He said he had arrived late.)
Perfect -> pluperfect. "He terminado" -> Dijo que había terminado. (He said he had finished.)
Future -> conditional. "Vendré" -> Dijo que vendría. (He said he would come.)
Present subjunctive -> imperfect subjunctive. "Quiero que vengas" -> Dijo que quería que vinieras. (He said he wanted you to come.)

Notice the preterite and the perfect both land on the same place, the pluperfect: había llegado, había terminado. Spanish does not keep them apart in the report.

The tenses that stay put

Two tenses are already one step back, so the backshift has nowhere to send them. They do not change.

Imperfect stays imperfect. "Trabajaba mucho" -> Dijo que trabajaba mucho. (He said he used to work a lot.)
Conditional stays conditional. "Iría contigo" -> Dijo que iría contigo. (He said he would go with you.)

This is why the imperfect carries a double load in reported speech: it is both the report of a present (estoy -> estaba) and the unchanged report of an original imperfect. The context tells you which.

When the reporting verb is present, nothing shifts

The backshift is triggered only by a past reporting verb. If you report in the present - dice que, comenta que, explica que - the original tense stays exactly as spoken.

"Estoy cansado" -> Dice que está cansado. (He says he is tired.)
"Llegué tarde" -> Dice que llegó tarde. (He says he arrived late.)
"Vendré" -> Dice que vendrá. (He says he will come.)

So the same original words, estoy cansado, give dice que está cansado with a present reporting verb but dijo que estaba cansado with a past one. The reporting verb's tense, not the original, decides whether anything moves.

The smaller shifts: pronouns, possessives, deixis

Around the tense move sit the same adjustments English makes, because the reporter is no longer the speaker and the moment of speaking has passed.

Pronouns shift to the reporter's point of view. The original yo becomes él / ella; tú becomes yo if the report is by the person addressed.

"Yo tengo razón" -> Dijo que él tenía razón. (He said he was right.)
"Tú no escuchas" (said to me) -> Dijo que yo no escuchaba. (He said I didn't listen.)

Possessives shift the same way. Mi becomes su, nuestro becomes suyo.

"Es mi coche" -> Dijo que era su coche. (He said it was his car.)

Time and place words move away from the here-and-now. This is the deixis shift.

hoy -> aquel día (today -> that day)
ayer -> el día anterior (yesterday -> the day before)
mañana -> al día siguiente (tomorrow -> the next day)
aquí -> allí (here -> there)
este -> aquel (this -> that)
ahora -> entonces (now -> then)

So "Llego mañana" reported in the past becomes Dijo que llegaba al día siguiente: present to imperfect for the tense, mañana to al día siguiente for the time.

que is obligatory

English drops the conjunction without a thought: he said he was tired, no "that" required. Spanish never does. The que after the reporting verb is grammatically obligatory.

Correct: Dijo que estaba cansado.
Wrong: Dijo estaba cansado.

This holds for every reporting verb - comentó que, explicó que, contestó que, añadió que - and it is not a matter of register. Leaving que out is an error, not a casual shortcut.

Worked examples

"Estoy en casa" -> Dijo que estaba en casa. (He said he was at home.) - present to imperfect.
"Compré el billete ayer" -> Dijo que había comprado el billete el día anterior. (He said he had bought the ticket the day before.) - preterite to pluperfect, ayer to el día anterior.
"Te ayudaré mañana" -> Me dijo que me ayudaría al día siguiente. (He told me he would help me the next day.) - future to conditional, deixis shift, pronoun shift.
"No he visto a nadie" -> Dijo que no había visto a nadie. (He said he hadn't seen anyone.) - perfect to pluperfect.
"Quiero que estudies más" -> Dijo que quería que estudiara más. (He said he wanted me to study more.) - present subjunctive to imperfect subjunctive.
"Vivía aquí de niño" -> Dijo que vivía allí de niño. (He said he used to live there as a child.) - imperfect stays, aquí to allí.

Common mistakes English speakers make

Dropping que. Copying English, learners write Dijo estaba cansado or Comentó iba a llover. Spanish requires the conjunction every time: Dijo que estaba cansado, Comentó que iba a llover. If there is a reporting verb, there is a que.

Backshifting after a present reporting verb. Producing Dice que estaba cansado for "he says he is tired" over-applies the rule. Dice is present, so nothing shifts: Dice que está cansado. The backshift is the past reporting verb's job alone.

Shifting the imperfect or conditional further. Hunting for a "more past" form of an original imperfect gives errors like Dijo que había trabajado mucho for "he said he used to work a lot". The imperfect is already as far back as it goes: Dijo que trabajaba mucho. Same for the conditional - iría stays iría.

Keeping the present subjunctive. Writing Dijo que quería que vengas mixes a past frame with a present subjunctive. After a past reporting verb the subjunctive backshifts too: Dijo que quería que vinieras. The sequence of tenses pulls the subjunctive back along with everything else.

Forgetting the deixis shift. Leaving hoy, mañana, aquí untouched - Dijo que llegaba mañana - clashes with the past frame. Move them: Dijo que llegaba al día siguiente. The report is no longer anchored to the original moment.

Get the backshift table, the present-reporting-verb exception and the obligatory que straight, and reported speech is just tense selection. The forms are ones you already own; reported speech only tells you which to reach for.