Is negative funds a feature?

[planetfall]

I'm only into my 6th game at immortal level and I was so focused on military and defense that I didn't notice funding until later in game, about turn 85. Opps, I was running a budget of -10 and expected game to end for lack of funds the next turn. But that did not happen. I was in dark age if that matters. Naturally, paused builds that costs funds and worked on bringing up commerical and mining luxuries.

But is negative funding ok under certain situations?