By the time they are 4-5 they become quite capable of doing many things. A good place to start is cleaning the house. You are, at least in these parts, going to pay an adult at least $20 per hour to convince anyone to show up – or $20 per hour to yourself if nobody else does. If we assume 30 minutes of work each day, that's $3,650 over the course of the year.
Studies that focus on what it actually costs to raise a child – not what it costs to raise a child and stroke parent egos – suggest that it is more like $4,000 per year to raise a child. So at this relatively young age are only in deficit by a few hundred dollars after a year. However, their capabilities ramp up quickly from there. If a teenager is only able to contribute $3k worth of value or less per year, you have failed them miserably[1].
[1] Or they have some kind of severe disability. That is the dice you do have to roll, but is statistically uncommon.
Studies that focus on what it actually costs to raise a child – not what it costs to raise a child and stroke parent egos – suggest that it is more like $4,000 per year to raise a child. So at this relatively young age are only in deficit by a few hundred dollars after a year. However, their capabilities ramp up quickly from there. If a teenager is only able to contribute $3k worth of value or less per year, you have failed them miserably[1].
[1] Or they have some kind of severe disability. That is the dice you do have to roll, but is statistically uncommon.