De or het indelingsplan?

The correct Dutch article is:

het indelingsplan

How to use indelingsplan

the indelingsplanhet indelingsplan
this indelingsplandit indelingsplan
that indelingsplandat indelingsplan
our indelingsplanons indelingsplan
your indelingsplanjouw indelingsplan
every indelingsplanelk indelingsplan
which indelingsplan?welk indelingsplan?
a big indelingsplan / the big indelingsplaneen groot indelingsplan, het grote indelingsplan

Dutch words ending in indelingsplan

herindelingsplan

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