Disclaimer:Naruto isn't mine
Being a dad means paying down all the debt you've piled up until now. It's easy enough to do since your wife doesn't feel like eating or leaving the house.
Iruka had managed to live a completely debt-free life thanks to his planning and organizational skills. Kakashi on other hand, wasn't drowning in debt, but had a little bit due to Icha Icha books, movies, and the like.
It was actually quite easy to get rid of debt. Kakashi wondered why he didn't do it sooner. Iruka never wanted to leave the house claiming he was to gross to be looked at and hated the thought of eating calorie-laden restaurant food.
Monetary speaking, it was the healthiest nine months of Kakashi's life.