Finance category

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Subject-To Cash Flow Calculator

Subject-to: buyer takes title, seller's existing mortgage stays in place. Buyer makes the payments directly. Common for distressed sellers who need out and investors wanting low-rate assumption. This calculator models cash flow on the deal including due-on-sale risk.

Purchase price

Existing loan balance (kept in place)

Cash to seller at close

Inherited P&I

Monthly property tax

Monthly insurance

Monthly HOA

Rental income

Vacancy %

Management + maintenance

Legal setup cost (one-time)

Monthly cash flow

$75

Annual cash flow

$900

Cash-on-cash ROI

7.2%

Total cash invested

$12,500

Effective rent (after vacancy)

$2,115

Total monthly cost

$2,040

Instant equity (price − loan)

$45,000

How the math works

Rent $2,250 × 94% vacancy = $2,115 effective. Minus $1,380 P&I + $290 tax + $95 ins + $275 mgmt = $2,040. Monthly cash $75 = $900/yr. On $12,500 invested: 7.2% cash-on-cash. Plus $45K instant equity.

Subject-to shines when the seller is motivated and the existing loan is low-rate. A 3.5% assumed mortgage vs 6.75% new loan = hundreds of dollars a month in better cash flow. Do the legal setup right and keep reserves for the payment no matter what.

Editorial noteMaintained by EveryCalc - Reviewed June 2026

EveryCalc calculators are designed for fast, practical estimates with transparent inputs and no required account. We use plain formulas, visible assumptions, and related tools so visitors can check the result from more than one angle.

Results are informational only. For financial, tax, legal, medical, construction, or other high-impact decisions, verify the output against primary sources or a qualified professional.

Learn more about our review process on the EveryCalc methodology page.

How this calculator works

What this page estimates

This Subject-To Cash Flow Calculator is built to give a quick, browser-based estimate for subject-to cash flow. Subject-to: buyer takes title, seller's existing mortgage stays in place. Buyer makes the payments directly. Common for distressed sellers who need out and investors wanting low-rate assumption. This calculator models cash flow on the deal including due-on-sale risk. The inputs stay on the page during normal use, and the result should be treated as an estimate for planning, comparison, or education rather than professional advice.

Calculation approach

The calculator applies the standard relationship implied by the inputs, then formats the answer so it can be checked and reused. For finance tools, the most important step is using consistent units, rates, time periods, and assumptions before comparing the result with another calculator or outside quote.

Example workflow

For example, start with a realistic value you already know, change one input at a time, and watch how the answer moves. That makes it easier to tell whether the result is being driven by the main amount, the rate, the time period, or a unit conversion.

Practical checks

Use current, real-world numbers when the result affects money, health, tax, or legal decisions.
Run a low, base, and high case when the inputs are estimates.
Check the related calculators below when the next decision depends on a different assumption.

How to interpret the subject-to cash flow result

Best use

Use the result as a planning number for comparing payments, rates, returns, tax reserves, or cash-flow choices before you request a quote or make a commitment.

Cross-check

Compare the answer with the contract, lender estimate, tax form, brokerage statement, payroll record, or invoice that will control the real-world outcome.

Watch for

Do not rely on a single optimistic rate, return, or fee assumption. Money pages work best when you run low, base, and high cases and keep professional advice separate from the estimate.

This page belongs to the Finance calculator library, so the answer should be read in the context of the decision you are modeling rather than as a universal rule.

Before relying on this subject-to cash flow estimate

Most calculator mistakes come from the inputs, not the arithmetic. Use this short audit before you reuse the answer in a spreadsheet, quote, application, or important conversation.

Confirm source numbers

Match balances, rates, fees, taxes, income, and payment dates against the lender quote, payroll record, tax form, statement, invoice, or contract.

Separate cash flow from total cost

A lower monthly payment can still cost more over time if fees, interest, taxes, or a longer term are hidden in the structure.

Run conservative cases

Test at least one higher-cost or lower-return case before using the output for a purchase, refinance, investment, loan, or tax decision.

Rerun this page when the rate, price, term, fee, tax rule, income, expense, or expected holding period changes.

How to Use

Enter purchase terms: inherited mortgage P&I, tax, insurance, HOA.
Enter rental income and operating cost.
See net monthly cash flow and ROI on any cash you put in.

Frequently Asked Questions

What's due-on-sale risk?

Most conventional mortgages have a due-on-sale clause — lender can call the loan in full if the borrower transfers title without consent. In practice, lenders rarely enforce on paying-current loans, but it's real risk. Dodd-Frank makes enforcement harder but not impossible.

How do I protect the seller?

Put property in a land trust and assign beneficial interest. Mortgage still reads seller's name but trust mechanics provide legal insulation. Have a RE attorney draft to ensure state-specific compliance.

Who pays what tax?

Buyer is now on title — pays property tax directly. Escrow can continue servicing through the old mortgage's escrow account (lender typically doesn't notice title change). Alternatively, buyer pays escrow separately.

Is subject-to legal?

Yes everywhere in the US, but enforceability varies by state. All parties need full disclosure (seller knows they're still on the mortgage). Consult a RE attorney and make sure your paperwork is airtight.