Learn English – due to vs because of

AHDEL (and Collins Cobuild) disagree with the dogmatic

'due to must be preceded by and followed by a noun phrase'

It offers [bolding mine]:

due to prep. Because of.

Usage Note: Due to has been widely used for many years as a compound preposition like owing to, but some critics have insisted that due should be used only as an adjective. According to this view, it is incorrect to say The concert was canceled due to the rain, but acceptable to say The cancellation of the concert was due to the rain, where due continues to function as an adjective modifying cancellation.

This seems a fine point, however, and since due to is widely used and understood, there seems little reason to avoid using it as a preposition.

Taking Oxford Dictionaries as one available for free:

You’re more than due for a vacation

uses

1.2(Of a person) having reached a point where the thing mentioned is required or owed:

Hence:

You have spend too much time not on vacation, and it is about time you took one.

But

You’re more than due a vacation

uses

1.3(Of a thing) required or owed as a legal or moral obligation:

Hence:

Your employers owe you a vacation.

This would also correspond with the sense "1. Owed or owing." at wiktionary which also has an example that is of a more directly comparable form ("He is due four weeks of back pay"). Wiktionary though while often excellent can be dangerous to rely on due to its wiki-based nature, especially when not backed up with quotations.