The perfect auxiliaries hebben and zijn are used to form perfect tenses: whereas the simple present in the primeless examples in (13) presents the eventualities of Marie walking on the moor and Jan reading a book as ongoing events in the present-tense interval, the present perfect in the primed examples presents the same eventualities as discrete units that are bounded within the present-tense interval. There are reasons, however, not to hold the auxiliary but the past participle responsible for the expression of this perfective meaning aspect; we refer the reader to Section 6.2.4 for the motivation of this claim, and to Section 1.5.1 for a more detailed discussion of the semantic interpretation of the present/past perfect tenses.

The choice between the perfect auxiliaries hebben and zijn is related to the status of the verb that they select: zijn'to be' is used with telic unaccusative verbs, whereas hebben is used in all other cases; see Table 3 in Section 2.1.2, sub V, and Table 5 in Section 2.1.3, sub IIH. In order not to have to repeat the detailed discussion of unaccusativity and its relevance for auxiliary selection in Section 2.1, we will illustrate the role of unaccusativity here by means of the monadic verbs lachen'to laugh' and vallen'to fall' only. The verb lachen is not unaccusative as is clear from the fact that it allows impersonal passivization; it therefore takes hebben as its perfect auxiliary. The verb vallen is an unaccusative verb as is clear from the fact that the participle can be used as an attributive modifier of a noun that corresponds to the subject of the corresponding active sentence; it therefore takes zijn as its perfect auxiliary.

The role of telicity can be demonstrated by means of the examples in (15). The unaccusative verbs drijven'to float' and bloeden'to bleed' are atelic and therefore take hebben as their perfect auxiliary. However, when we add the complementives weg'away' and dood'dead', the constructions as a whole become telic and, as a result, the verbs take the perfect auxiliary zijn. For a more detailed and systematic discussion of unaccusativity and telicity, as well as their relevance for auxiliary selection, we refer the reader to Section 2.1.

Another factor that needs mentioning is that for some (especially Flemish) speakers the choice between hebben and zijn is not necessarily determined by the verb that it immediately governs but may also be determined by some more deeply embedded verb. In (16), the verb moeten selects the auxiliary hebben but nevertheless some speakers allow or even prefer zijn because the more deeply embedded unaccusative verbs komen'to come' and gaan'to go' select zijn; example (16a) is taken from Haeseryn et al. (1997:81) and example (16b) is provided by one of our own Flemish informants.

The projection of the main verb is embedded under the finite auxiliary: the representation is [... Aux [... V[-finite] ...]]. We may therefore assume that the morphological form of the main verb is governed by the auxiliary (in the same way that a main verb may govern the case form of its nominal arguments in languages that have morphological case). The examples in the previous subsections have already shown that the non-finite main verb governed by the perfect auxiliary surfaces as a past participle if the verb cluster consists of no more that two verbs, that is, if the clause contains no other verbs than the perfect auxiliary and the main verb; if the verb surfaces as an infinitive, the resulting structure is unacceptable. This is illustrated in the examples in (17).

A phenomenon that has attracted a great deal of attention in the syntactic descriptions of Dutch is that the auxiliary and the main verb do not have a fixed place with respect to each other in clause-final position: the examples in (18) show that past participles may either precede or follow the finite auxiliary.

When we consider the regional spread of the two word orders, it seems that the order aux–part is only found in a restricted part of the Dutch-speaking area, which happens to include the prestigious varieties of the standard language spoken in the west/middle region of this area; the maps in Pauwels (1953), Gerritsen (1991) and Barbiers et al. (2005) all show that this order is rare in the varieties of Dutch spoken in Flanders and the northern part of the Netherlands. For this reason we have marked this order with a percentage sign.
      Speakers who allow the order aux–part normally also allow the order part-aux. There is reason for assuming that the latter order (part-aux) is in fact the unmarked one for such speakers given that Barbiers et al. (2005) found that they rarely invert this order in reproduction tasks.
      It now seems generally accepted that the use of the aux–part order is characteristic for written Dutch and the more formal registers of spoken Dutch (despite that it frequently occurs in the more casual speech of many speakers); see Haeseryn (1990:ch.2) for a good review of the relevant literature on this issue. A corpus analysis by De Sutter (2005/2007) suggests that even in written Dutch the aux–part order is secondary since this order is mainly used in relatively simple sentences; there is a negative correlation between the complexity of utterances and the frequency of the aux–part order.
      The finding that the aux–part order is marked (perhaps even artificial) for most speakers of Dutch seems to be in line with the fact that this order was introduced in the 16th century and diligently promoted by normative grammarians, and that it still seems to be prescribed for journals and newspapers; see Coussé (2008:ch.10) and Van der Horst (2008:1984ff.). The attempt to promote this order has in fact been very successful since for most present-day speakers who allow this order, it simply functions as an alternative realization of the more widely accepted part-aux order.
      The factors favoring the selection of one order over the other are complex and have only been investigated for written language. The studies reviewed in Haeseryn (1990:46ff.), for example, provide evidence that the presence of a verbal particle or some other accent-bearing material preceding the verb cluster favors the use of the aux-part order, whereas the presence of material following the verb cluster disfavors it. De Sutter's (2005/2007) tested some of the more specific claims made in the literature on the basis of a more recent newspaper corpus, and found that: