De or het mandaatregeling?

The correct Dutch article is:

de mandaatregeling

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

How to use mandaatregeling

the mandaatregelingde mandaatregeling
this mandaatregelingdeze mandaatregeling
that mandaatregelingdie mandaatregeling
our mandaatregelingonze mandaatregeling
your mandaatregelingjouw mandaatregeling
every mandaatregelingelke mandaatregeling
which mandaatregeling?welke mandaatregeling?
a big mandaatregeling / the big mandaatregelingeen grote mandaatregeling, de grote mandaatregeling