De or het taillering?

The correct Dutch article is:

de taillering

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

How to use taillering

the tailleringde taillering
this tailleringdeze taillering
that tailleringdie taillering
our tailleringonze taillering
your tailleringjouw taillering
every tailleringelke taillering
which taillering?welke taillering?
a big taillering / the big tailleringeen grote taillering, de grote taillering

Dutch words ending in taillering

detaillering | ravitaillering

In compound words, the last part decides the article. See the rule