Can someone point to some strict rules or rules of thumb for using être/avoir for passé composé for irregular verbs? Does it follow from change of radical for different tense?

In German, a change of the radical vowel means, you have to use avoir. But there are also some verbs, for which one can use either avoir or être to build Perfect, or at least one usage is more common in the south and the other in the north region of Germany. A rough rule in German and in general Germanic languages is that "weak verbs" and intransitive verbs mostly need être to build the perfect as far as I know. But French has 3 times as many irregular verbs as German, so maybe there are very different rules. Are my hints and assumptions above a good start?

PS: This site lists the rules for German verbs very accurately (in German).

  • “A change of the radical vowel means, you have to use avoir”. I don't think there's any kind of rule like that, or I don't know what you mean by “A change of the radical vowel”. “Ich habe geschrieben.” and “Ich bin geblieben.” Anything that I'm overlooking? Commented Jan 8, 2014 at 11:26
  • Btw, I think the correspondence between German and French is very strong with this respect. There are only a few exceptions including some “movement-related” verbs that have close but different usages, like fahren (go with a car, etc.) vs conduire (use a wheel, etc.), which explain the difference in the choice of the auxiliary. Of course passive is the most recurrent (but consistent) difference “sein _ worden” vs “avoir été _”. Commented Jan 8, 2014 at 11:34
  • @StéphaneGimenez I read an older rule going "Ich singe - Ich sang - Ich habe gesungen - radical vowel change i - o - u" It makes sense to me that in very past tense was maybe more expressed by phonetic change than nowadays with auxiliary verbs, but thats just my guess
    – Hauser
    Commented Jan 8, 2014 at 20:37

1 Answer 1


The comparison with German is not going to be very helpful, in general. Here are rules of thumb for French:

  1. All reflexive and reciprocal verbs are conjugated with être
  2. Most of the rest of the verbs are conjugated with avoir
  3. Except for a short list of verbs, which, when used intransitively, are conjugated with être

The rule of thumb for the short list is that they generally indicate some motion or movement. They are often assembled into a mnemonic diagram called "la maison d'être" such as you can easily find on the web (like here).

An image replacing the dead link above

It is worth it to simply memorize this list since the same rules apply not only to Passé Composé but to all compound tenses.

  • To complement this answer, here's a flow chart of the decision tree.
    – Luke Sawczak
    Commented Nov 2, 2019 at 22:15

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