Prior to my daughter being born, I was unemployed, in a Master's program and we were living on my husband's $26,000 grad salary, our tenant's gave us money for retirement savings (about $4000/year) and our roommate gave us some wiggle room (about $200/month). Then our daughter was born, and I got into the PhD program. My salary is $25,000 but much of it is taken up by our daughter's expenses (daycare is $244/week), taxes and retirement savings ($625/month plus 3% of my salary to a pension). We now use the income from the tenants for side savings/debt pay down because my husband is graduating and our EF was mostly money from subsidized student loans so I want to pay all of his student loans down, save an EF and save for moving in 3 years. So, that is my reasoning for staying at 15% retirement saving for now. But then I was thinking, we only really need $30K in retirement (not including inflation) because we don't plan to retire till we pay our kids way (we plan to have a second kid) through college, not the whole 51-55K.
I wondered how other MMM parents considered children's expenses. They are not savings, but they are not spending account for in retirement.