Future subjunctive and legal / archaic forms

What it is

The future subjunctive (futuro de subjuntivo: hablare, tuviere, fuere) once marked open, future events in conditions and relative clauses. Modern Spanish has replaced it everywhere except in two places: legal and administrative texts that keep old formulas, and a handful of fixed expressions. At C2 you need to recognise it in a contract, a law or a set of contest rules, and to use the lexicalised formulas (sea como fuere) naturally. You never need to build it in conversation.

How to form it

Take the third-person plural of the preterite, drop -ron and add -re. Every irregularity of the preterite carries over.

The compound form is hubiere + participle: Si para esa fecha no se hubiere resuelto… The stem is the one you already know from the imperfect subjunctive in -ra (tuviera), with e instead of a.

When you will meet it

1. Laws, regulations, contracts, contest rules. Drafters keep it in conditions and in relative clauses that define who is affected:

• El que infringiere esta norma será sancionado.Whoever breaches this rule shall be penalised.relative clause that defines the offender
• Si hubiere empate, decidirá el voto de calidad.In the event of a tie, the casting vote shall decide.open condition
• Si procediere, se abonará la diferencia.If applicable, the difference shall be refunded.formula: si procediere = if applicable

2. Fixed expressions. These are alive in educated speech and writing:

• sea como fuere: be that as it may
• venga lo que viniere: come what may (also venga lo que venga)
• Adonde fueres, haz lo que vieres.: when in Rome, do as the Romans do
• o lo que fuere: or whatever (formal or ironic)

The modern equivalent

When you paraphrase a legal text in your own words, replace each form with what ordinary Spanish uses in the same slot:

Rule of thumb: after si, the present indicative; everywhere else, the present subjunctive.

Reading a clause step by step

Quien resultare premiado y no aceptare el premio en el plazo de diez días perderá todo derecho sobre él.

• resultare, aceptare: future subjunctive inside a relative clause that defines a person. Read it as "whoever is… and does not…".
• perderá: the ordinary future states the legal consequence ("shall lose").
• Modern paraphrase: Quien resulte premiado y no acepte el premio en diez días perderá el derecho a recibirlo.

Try it

Five quick exercises from this topic's training set:

Contrasts and traps

• hablare ≠ hablaré. The written accent changes the form: hablaré is the ordinary future ("I will speak"); hablare, stressed on -bla-, is the future subjunctive. In a law, el que no pagare means "whoever fails to pay".
• -re ≠ -ra. si hubiere (legal, open condition) is not si hubiera (hypothetical). When you modernise, go to si hay, not to si hubiera.
• Don't produce it in speech. Si vinieres mañana… sounds like a nineteenth-century code. Say Si vienes mañana…
• sea como fuere / sea como sea. Both are correct; the blend sea como fuera is frequent, but style guides reject it.

For Portuguese speakers

This is the C2 topic where Portuguese helps you read and hurts you speak. The Portuguese futuro do subjuntivo is alive (se eu for, quando você tiver, quem quiser), so legal Spanish feels familiar. In ordinary Spanish, though, conditions take si + present indicative (si puedo) and time or relative clauses take the present subjunctive (cuando tengas, quien quiera). Never carry quando tiver over as cuando tuviere or cuando tuviera: it is cuando tenga.