De or het depotwerking?

The correct Dutch article is:

de depotwerking

Rule Words ending in -ing: almost always de. See the rule

How to use depotwerking

the depotwerkingde depotwerking
this depotwerkingdeze depotwerking
that depotwerkingdie depotwerking
our depotwerkingonze depotwerking
your depotwerkingjouw depotwerking
every depotwerkingelke depotwerking
which depotwerking?welke depotwerking?
a big depotwerking / the big depotwerkingeen grote depotwerking, de grote depotwerking