Future Subjunctive

The future subjunctive is supposed to be used in Spanish when a verb or expression requiring the subjunctive in the main clause is in the present or future and refers to a future action.

However, the future subjunctive is becoming obsolete, it tends to be replaced by the present subjunctive. The Spanish future subjunctive may still be found in writing, such as literature and and legal documents.

The future subjunctive is conjugated much like the -RA form of the imperfect subjunctive: take the third person plural preterite form of any regular, irregular, or stem-changing verb, drop the -RON ending to find the radical, and add the appropriate ending:

future subjunctive endings

yo 	-re      nosotros     -remos
tú 	-res     vosotros     -reis
él 	-re      ellos        -ren

for example...
HABLAR

 	  	  	 
yo 	hablare       nosotros 	habláremos
tú 	hablares      vosotros 	hablareis
él 	hablare       ellos 	hablaren

TENER

 
yo 	tuviere       nosotros   tuviéremos
tú 	tuvieres      vosotros   tuviereis
él 	tuviere       ellos      tuvieren

Notes:

* The yo and él forms of the future subjunctive are identical.
* In the nosotros form, an acute accent is added to the last vowel in the radical.