De or het spellingregeling?

The correct Dutch article is:

de spellingregeling

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

How to use spellingregeling

the spellingregelingde spellingregeling
this spellingregelingdeze spellingregeling
that spellingregelingdie spellingregeling
our spellingregelingonze spellingregeling
your spellingregelingjouw spellingregeling
every spellingregelingelke spellingregeling
which spellingregeling?welke spellingregeling?
a big spellingregeling / the big spellingregelingeen grote spellingregeling, de grote spellingregeling