He claims that he [had to]/[has had to] work on this book for 3 years.

1) Er behauptet, dass er an diesem Buch 3 Jahre hat arbeitet müssen.
2) Er behauptet, dass er an diesem Buch 3 Jahre hat arbeiten müssen.

The book I am reading says the verb haben must be before the 2 infinitives but gives option 1) as an example, i.e. there're no 2 infinitives there?! And so I am confused.

  • 1
    @Loong No, it's not a duplicate, I am aware of this rule. So there must be 2 infinitives there and the book has a typo, right? I just want a confirmation that 1) is wrong while 2) is correct. Apr 9, 2015 at 18:14
  • I see; well all right then, I retract my close vote.
    – user9551
    Apr 9, 2015 at 18:17
  • 1
    Without knowing the context of your book, I tend towards the view that you are right. The sentence No 2 correctly includes two infinitives (arbeiten and müssen).
    – user9551
    Apr 9, 2015 at 18:26
  • 5
    Version 1) is incorrect.
    – hellcode
    Apr 9, 2015 at 18:26
  • 1
    OK. Then, yes, it’s probably just a typo.
    – user9551
    Apr 9, 2015 at 18:36

2 Answers 2


It was already answered in the comments, but I'll give a detailed answer in case more people stumble across this.

This construction, as I assume you guessed from the English sentence, is a special form of the Perfekt. Many modal verbs, especially if they are accompagnied by an infinitive, use this alternative form of the past participle which resembles the infinitive. I disagree with calling it infinitive though, because it's grammatical purpose is that of a past participle, not of an infinitive.

(Minor side note: It also changes the word order, which in a standard perfect tense sentence would have hat last.)

The second verb (arbeiten) has to be an infinitive (because it's an infinitive construction), so it has to end in n. Thus, there is a typing error in your book.

Just for completeness, the correct sentences:

»Ich musste an dem Buch drei Jahre arbeiten.«
Er behauptet, dass er an diesem Buch drei Jahre arbeiten musste.
»Ich habe an diesem Buch drei Jahre arbeiten müssen.«
Er behauptet, dass er an diesem Buch drei Jahre hat arbeiten müssen.


Version 2 is the correct one.

Edit example:

"arbeiten" is the infinitive governed by the verb "müssen" which can't stand alone:

Er muss hart arbeiten.

Transformed to past perfect tense, "arbeiten" is still an infinitive because the finite verb changes, while the structure itself doesn't:

Er hat hart arbeiten müssen.

  • 1
    This answer has been opted to close, but I think it can be easily improved and reviewing it, I don't want to discourage a user who just joined the site. Just keep in mind that answers should be precisely to the point the shorter they are, and should lead to a more general insight into what the question implies, thus helping more people than just the person asking. Please don't post answers as dry one-liners like a quick acclamation while hurrying past, but weigh every word as to give the proper answer to the best of your ability. Apr 11, 2015 at 6:25

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