real estate cash flowmonthly cash flowrental incomeinvestment cash flowproperty finance
You collect €750 in rent every month. Your mortgage payment is €470. That leaves €280. Not bad, right?
Except property taxes, landlord insurance, condo fees, management costs, and maintenance reserves haven't been deducted yet. Once you subtract everything, your real cash flow might shrink to a few dozen euros — or slip into the red entirely.
Monthly real estate cash flow is exactly that calculation: the amount left over (or missing) each month after paying absolutely everything. Think of it as your checking account balance, but dedicated to a single property. If the balance is positive, your investment pays for itself and generates income. If it's negative, you're dipping into personal savings every single month.
Why track this monthly instead of once a year? Because expenses don't arrive in neat, predictable waves. A month of vacancy here, an unexpected condo assessment there, a utility adjustment you didn't see coming. Monitoring your monthly cash flow lets you spot trouble early instead of discovering it after the damage is done.
The formula fits on one line:
Monthly cash flow = Monthly rental income − Total monthly expenses
The result puts you in one of three situations:
This cash flow figure is one of the key metrics every investor should track. It complements other indicators like gross, net, and cash-on-cash yield, which measure annual performance rather than monthly health.
Before you calculate monthly cash flow, list everything your property brings in each month:
One critical rule: only count amounts actually received. If your tenant pays late or if the unit sits vacant for a month, your real income drops accordingly. Planning around collected rent — not theoretical rent — keeps your calculation honest.
This is where most beginner investors underestimate costs. Here's the full list:
Time to get hands-on. Grab a spreadsheet or a sheet of paper.
Base rent + recoverable charges + ancillary income. For example: €750 + €50 in recoverable charges = €800 gross income.
Group each cost item. Annual charges (property taxes, insurance) get divided by 12. Write down everything, even small amounts.
This gives you the net cash flow before taxes. Positive? Your property generates cash. Negative? Every month digs a hole in your savings.
Under France's unfurnished rental regime (régime réel), rental income is taxed at your marginal rate plus 17.2% in social contributions, after deducting allowable expenses. Under the LMNP furnished rental regime, accounting depreciation can reduce — or even eliminate — your taxable base. This fiscal choice radically changes your real cash flow. For details on deductible expenses, see our net rental yield calculation method.
Let's take a 45 m² one-bedroom apartment in Lyon's 7th arrondissement, purchased for €185,000 with a 20-year loan at 3.2%.
Monthly income:
| Item | Amount |
|---|---|
| Base rent | €750 |
| Recoverable charges | €50 |
| Total income | €800 |
Monthly expenses:
| Item | Amount |
|---|---|
| Mortgage payment | €1,048 |
| Property taxes (÷ 12) | €85 |
| Landlord insurance (÷ 12) | €15 |
| Non-recoverable condo fees | €55 |
| Vacancy reserve (8%) | €60 |
| Maintenance reserve (4%) | €30 |
| Total expenses | €1,293 |
Net cash flow before taxes: €800 − €1,293 = −€493
Negative result. This Lyon apartment requires €493 per month out of pocket. Is that a dealbreaker? Not necessarily — but you absolutely need to know about it before signing the purchase agreement. Running your DSCR ratio before buying helps you avoid this kind of surprise.
Positive cash flow is obviously the goal. But let's be honest: with mortgage rates around 3.2% in 2026 and prices still elevated in major French cities, reaching positive cash flow without a significant down payment has become very difficult. Investors who purchased between 2015 and 2021 at sub-2% rates had a much easier path.
Does that mean negative cash flow is always a disaster? No. Some investors accept a moderate monthly outlay, betting on capital gains at resale or long-term wealth building through equity. A property that costs you €200 per month but appreciates 3% per year may still be a sound investment over 15 years.
The real mistake is not knowing your cash flow at all and discovering the gap in your budget three months too late.
If your numbers look tight, three practical paths can help:
Tracking all of this in a spreadsheet works at first. But once you manage two or three properties, formulas multiply and Excel's limitations become obvious. At REIOS, we're building a tool that automates this tracking so you can focus on decisions, not data entry.