De or het maatregeling?

The correct Dutch article is:

de maatregeling

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

How to use maatregeling

the maatregelingde maatregeling
this maatregelingdeze maatregeling
that maatregelingdie maatregeling
our maatregelingonze maatregeling
your maatregelingjouw maatregeling
every maatregelingelke maatregeling
which maatregeling?welke maatregeling?
a big maatregeling / the big maatregelingeen grote maatregeling, de grote maatregeling

Dutch words ending in maatregeling

klimaatregeling

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