The future perfect (Futur II, vollendete Zukunft) expresses the assumption that an action will have been completed by the time of speaking, or by a particular point in the future.
1. The verb “werden” and Futur I
In order to form the Futur II tense (future perfect), we will, just as we do for the Futur I tense, use the auxiliary verb “werden” (will).
It is important to remember that the verb “werden” can also be used as a main verb. As a main verb, “werden” means to become or to get. (Ich werde müde – I am getting tired.)
To form the Futur I tense we use the formula “werden + infinitive verb”. In a future tense sentence, the conjugated form of werden is in second position (in regular word order), and the verb in the infinitive is moved to the end of the sentence.
Examples:
Ich werde morgen arbeiten. I will work tomorrow.
2. Futur II (The Future Perfect)
The future perfect tense is used when talking about a future moment in time, when something “will have happened”. In English and in German, we need to use the past participle in this construction, but using past participles in German is a bit more complicated (haben/sein).
The formula for the Futur II tense is “werden + past participle + inf. haben/sein”
If the verb that is used forms its participle with “haben”, we use haben in the Future II, and if it uses “sein”, we use “sein”.
Examples:
Ich werde die E-Mail geschrieben haben.
I will have written the email.
Ich werde zur Arbeit gegangen sein.
I will have gone to work.
Use Futur II to refer to actions that will take place in the future and that will have been completed in the future. You form sentences with the conjugated form of the auxiliary verb werden (will), the past participle of the verb, and the unconjugated form of the auxiliary haben (to have) or sein (to be).