MVP Prototype
Income & Expense Change Calculator
If monthly income changes and monthly expenses change, what happens to monthly margin? This prototype compares a current monthly scenario with a new monthly scenario using simplified user-entered assumptions.
Educational prototype only. This tool uses simplified user-entered assumptions and does not recommend a budget, spending level, savings target, or financial decision.
Results
Modeled monthly change
These outputs are illustrative and based only on the assumptions entered.
Main takeaway
Insight layer
What is driving this?
Income change
Expense change
Margin before and after
Amount absorbed
Largest category change
Category layer
Expense category comparison
This table shows which expense categories changed between the current and new scenario. It does not judge any change.
| Category | Current monthly amount | New monthly amount | Change |
|---|
How to read this result
- Income change shows how much monthly take-home pay changed.
- Expense change shows how much total monthly expenses changed.
- Current margin is current take-home pay minus current total expenses.
- New margin is new take-home pay minus new total expenses.
- Margin change shows whether the monthly gap between income and expenses changed.
- Percent absorbed shows how much of the income increase was taken up by expense changes, when income increased.
- Largest expense category change shows the category with the largest dollar change between scenarios.
This section explains the output; it does not tell anyone what to spend or save.
What would change this result?
This result would change if any user-entered assumption changed, including:
- Current monthly take-home pay
- New monthly take-home pay
- Any current monthly expense category
- Any new monthly expense category
In this prototype, the result changes because income and expenses are compared together. A higher income number does not automatically mean the monthly margin increases.
Formula in plain English
This tool adds the current expense categories and the new expense categories, subtracts each total from the matching take-home pay, then compares the two monthly margins.
When income increases, the tool also estimates how much of that increase is absorbed by expense changes.
What this teaches
Income changes and expense changes work together. A higher income number does not automatically mean the monthly margin changes by the same amount.
Key idea
A new income number only becomes meaningful after the new expense structure is considered too.
Some expense changes may come from lifestyle choices. Others may come from location, housing, transportation, work, required payments, or other circumstances.
This prototype is designed to explain income and expense structure, not recommend a budget or spending decision.
Assumptions used in this prototype
- Monthly take-home pay is user-entered.
- Expense category amounts are user-entered.
- Blank expense fields are treated as $0.00.
- The tool compares two simplified monthly snapshots.
- Taxes are not calculated.
- Benefits deductions are not calculated.
- Moving costs are not separately modeled unless included in the user-entered categories.
- One-time costs are not separately modeled.
- Savings are only included if the user includes them as an expense category.
- Debt payments are only included if the user includes them.
- No inflation adjustment is included.
- No annualized projection is included.
- This is a simplified educational prototype.
What this does not do
- This is not budgeting advice.
- This is not savings advice.
- This is not spending advice.
- This is not investment advice.
- This is not tax advice.
- This is not a financial plan.
- This is not a recommendation.
- This does not tell users what to spend, save, keep, remove, or change.
- This does not account for all real-life expenses, taxes, benefits, one-time costs, moving costs, family circumstances, or household needs.
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