Plan a personal budget from before-tax income and the expenses you actually pay. Enter each line as a monthly or yearly amount, add a combined tax rate, and see whether you have leftover money or a deficit — plus debt-to-income and a category breakdown.
DTI bands
| Back-end DTI | Category |
|---|---|
| Under 35% | Under 35% |
| 35% to under 50% | 35% to under 50% |
| 50% or more | 50% or more |
Examples
Default $80,000 salary
Salary $80,000, investments $1,000, other income $2,000, and a 28% tax rate give $83,000 before tax and $59,760 after tax. Expenses (with the $10,000 401(k) counted at $7,200) total $57,640, so leftover is $2,120 a year ($177 a month). DTI is 27.71% (under 35%); front-end DTI is 20.48%.
Rent at $4,000 a month
The same income with rent raised to $4,000 a month turns the plan into a $29,080 annual deficit ($2,423 a month). Back-end DTI jumps to 65.30% (very high).
Formula
Every amount is converted to an annual figure, then tax and pretax savings are applied:
annual(amount) = amount × 12 if monthly, else amount
gross = salary + pension + investments + other income
after-tax income = gross × (1 − tax rate)
pretax savings = pretax retirement contribution × (1 − tax rate)
college/other saving = amount entered
total expenses = housing + transportation + other debt + living
+ healthcare + education + pretax savings
+ other savings + miscellaneous
net = after-tax income − total expenses
monthly = round(annual / 12)
Back-end DTI uses gross income in the denominator. Housing in DTI is mortgage, rent, property tax, home insurance, and HOA — not utilities or maintenance. Loan payments (auto, student, credit card, other) add to back-end DTI only.
Income items are before tax. If you know take-home pay instead, either lower the tax rate toward zero or enter net pay as salary so you do not subtract tax twice.
Assumptions and limits
The single tax rate is an estimate applied to all gross income; the page does not calculate brackets, credits, payroll deductions, withholding, benefit premiums, or different tax treatment by income source. Pretax retirement savings are assumed fully deductible at that rate. College savings are treated as after-tax because federal deductibility is not assumed; any state benefit is outside the model. DTI ranges are descriptive planning bands, not lender approval rules.