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The basics
Add a child with a birth year, then divide costs into age-based stages. A new child starts with one stage covering ages 0 through 17; add daycare, school, college, or later support when those costs belong in your plan.
Choose the last age covered by each stage. Each stage has its own annual amount and change rule. Education stages can name a 529 or other account as their funding source.
Illustrative numbers
Give college its own funding source
Ages 0–17$12,000 a year for ordinary support
Ages 18–21$30,000 a year for college
College fundingA named 529 account first
At the stage boundary, the college budget replaces the earlier stage’s amount. If you also want to fund ordinary support, include it in the college-stage total or a separate spending entry.
Calculation transparency
How it works in MoneyWhatIf
- 01
Stages run back to back from birth. For an existing child, the projection includes only the portion still ahead. Turning a child off removes its modeled costs.
- 02
Child costs enter the same spending and funding calculation as other expenses. Each stage can have an ordered list of accounts to draw from.
- 03
The general withdrawal order leaves 529 accounts out. A named education withdrawal can reach them; the plan relies on your funding declaration rather than checking individual tuition receipts.
- 04
Child ages also inform the modeled dependent-child window after a spouse’s death. Marketplace tax-family size is a separate field that you must supply.
Keep in mind
Model limits
Birth-year inputs use whole-year ages rather than exact birthdays.
The model does not determine education-expense eligibility, financial aid, or all 529 tax exceptions.
This explanation documents the planning model. It is educational, not individualized tax, legal, Medicare, or investment advice.
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The words behind it
Related financial terms
Plain-English definitions, with 2026 figures and worked examples, from the financial terms glossary.