French Rental Cash Flow Calculator (Net-Net, LMNP)

Enter rent, vacancy, charges, loan payment and LMNP tax regime to get the monthly cash flow after French tax.

Net-net rental cash flow: rent, costs, loan and tax per month

Net-net cash flow is what remains each month after expenses, the loan payment and tax on rent: (rent after vacancy − expenses − loan − tax) ÷ 12. With the default values, €850 of rent and a €620 loan payment leave a monthly shortfall of about €104 under the French LMNP real regime.

Step by step

  1. Rent collected = rent × 12 − (rent × 12 ÷ 52) × vacancy weeks.
  2. Expenses = property tax + landlord insurance + non-recoverable service charges × 12 + maintenance reserve (as % of rent collected). Operating income = rent collected − expenses.
  3. Tax = base × (marginal rate + 18.6% social levies on furnished lettings). Micro-BIC base: 50% of rent collected. LMNP real-regime base: operating income − 45% of gross rent, floored at zero.
  4. Annual cash flow = operating income − loan payments × 12 − tax, then divided by 12.

Default example

Rent of €850, 2 vacancy weeks: €10,200 − €392 = €9,808 collected. Expenses: €900 + €180 + €540 + €490 = €2,110, so operating income is €7,697. Under the real regime the base is €7,697 − €4,590 = €3,107 and tax €1,510 at a 30% marginal rate. Cash flow: €7,697 − €7,440 − €1,510 = −€1,253 a year, or −€104 a month. Under micro-BIC, tax rises to €2,383 and cash flow to −€177 a month.

Assumptions and limits

  • Under the real regime the tool does not depreciate the property; it uses a flat 45%-of-gross-rent deduction instead. The LMNP tax simulator computes depreciation in detail.
  • The loan payment includes principal; interest is not deducted separately. French rules; this is an estimate, not advice.

Sources and dates: 18.6% social levies on furnished lettings, French Social Security Financing Act for 2026 (Act 2025-1403 of 30 December 2025, article 12), from 2025 income, confirmed by impots.gouv.fr (page updated 17 July 2026); 50% micro-BIC allowance for long-term furnished lettings, impots.gouv.fr (updated 8 April 2026) (checked 14/10/2026)

Frequently Asked Questions

What is the net-net cash flow of a rental investment?

It is the monthly balance after rent collected, expenses, loan payment and tax. A negative figure is the amount you must top up each month: €104 in the default example under the LMNP real regime.

How is vacancy taken into account?

Each vacancy week removes 1/52 of annual rent. For €850 a month, two weeks mean €392 of lost rent a year, or 3.8% of rent.

Why is the LMNP real regime estimated with 45% of rent?

The calculator does not know the property price, so it cannot compute depreciation. It deducts a flat 45% of gross rent from operating income to approximate the depreciation effect. For an exact figure, the LMNP tax simulator asks for the price, works and furniture.

Which social levy rate applies to furnished rental income?

18.6% from 2025 income onward, compared with 17.2% before. The calculator applies 18.6% under both regimes: −€104 a month (real) and −€177 (micro-BIC) in the default example.

Is this tool really free?

Yes, all tools on Kristools are 100% free and accessible without registration.

Is my data protected?

Yes. All processing is performed directly and securely inside your browser. No personal data is sent to our servers.