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House hack cash flow

What is your net housing cost after rent from other units or rooms?

Your numbers

Net monthly housing cost

$1,794

Effective rent from other units / rooms$1,656
Share of PITI covered by rent51.7%

Tip. Educational estimate with the assumptions listed on this page. Not tax, legal, or investment advice.

Assumptions

  • You still live in the property. This is housing cost, not a pure investment CoC.
  • Vacancy applies only to the rented portion.
  • Tax benefits of owner-occupied vs rental allocation are excluded.

Explore the numbers

Examples

Load a scenario, then change one input at a time.

Example 1

Duplex

You live in one side.

Net monthly housing cost

$1,794

Example 2

Roommates

Two rooms at $900.

Net monthly housing cost

$1,416

Example 3

House pays you

Triplex with strong rents.

Net monthly housing cost

-$148

What this calculates

Subtract effective rent from housemates or extra units from PITI and owner-occupied operating costs to see what housing actually costs.

How to use it

  1. Use PITI from the mortgage tool, not a round number from memory.
  2. If you rent rooms, vacancy is roommate turnover.
  3. A negative net housing cost means the property pays you to live there — until a void month.

Common mistakes

  • Ignoring that you still need a bedroom when the tenant leaves.
  • Underwriting 100% occupancy on three rooms in a house you also occupy.
  • Forgetting utilities you agreed to cover.

Formula

Net housing = PITI + owner ops − rent × (1 − vacancy%).

FAQ

Is house hacking the same as a duplex rental?

You occupy part of it. Financing and tax treatment differ from a pure rental.

Can this be an STR on the other unit?

Yes, but then use STR occupancy and ops, not a simple vacancy percent.

Does this help with DTI?

Some lenders count a fraction of rental income. Do not assume 100% of this rent lands on the application.

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