Someone leaves on the 12th. The rent was debited on the 1st, the electricity lands on the 15th, and nobody knows how to cut that up.
The month started is owed
The simplest and most defensible rule: whoever leaves pays the current month in full. They lived there, their things were there, the lease was running. Cutting it by the day produces wrong figures and long conversations.
It is also closest to what a French lease says. Rent is monthly and payable in advance: it is not owed day by day, it is owed for the month. Leaving on the 12th does not create a debt of twelve thirty-firsts, it leaves a paid month for a flat vacated halfway through.
The one exception is about the notice date, not the moving date.
Notice runs to its end, boxes or no boxes
This is what flatshares discover too late.
Notice (préavis) is one month in a zone tendue, a high-demand area, which covers Lyon, Paris, Bordeaux, Lille and most large cities, and three months elsewhere. It starts when the registered letter is received, not when the person announces their departure over dinner.
During that notice, the person leaving owes the rent whether they sleep there or not. Handing back the keys on the 12th does not end the notice: it ends the occupation.
The solidarity clause, and the six months after
On a single lease with a solidarity clause (clause de solidarité), leaving does not erase the commitment overnight.
French law ends that liability six months after the end of their notice, or sooner if a new flatmate replaces them on the lease. In between, if rent goes unpaid, the landlord can claim it from them.
The practical consequence nobody likes hearing: until the replacement is on the lease, the person who left is still exposed. Getting the amendment signed is in everybody’s interest, not just the landlord’s.
What is settled separately
Cross-advances. If the person leaving paid everyone’s internet in March, their share is still owed. Those balances are settled at departure, not before, not after.
Make the list before they go, while everyone still remembers. Three items come up every time.
Bills fronted: internet, electricity, insurance. Each was paid by someone, and the others’ share is owed.
Shared durable purchases: the vacuum cleaner, the coffee machine, the shelves. They stay in the flat, and the person leaving sees nothing back unless you decided otherwise when buying. This is the most common source of resentment, and it is settled in twenty seconds if you talk about it.
The deposit. It is not returned when one flatmate leaves, it is returned at the end of the lease, which may be years later. The usual practice is for the replacement to buy out the leaver’s share on arrival. If nobody does, the person who left waits until the lease ends to see their money.
The following month
It splits between those who stay. If you were three and are now two, each goes from a third to a half. That is decided before the departure, not on the 5th of the next month when the debit lands.
The jump is steep and worth putting a figure on. On 1,100 € of rent, going from three to two takes each share from 367 to 550 €, which is 183 € more per person per month. Over three months of searching, that is 549 € each for those who stay.
Which is exactly why the search for a replacement starts on the day of the announcement, not the day of the departure.
No inventory for one person
There is none, and it causes misunderstandings.
The inventory (état des lieux) is done when entering and leaving the property, not when each person arrives and leaves. When somebody goes alone, nothing is formally recorded, and any damage from their stay will be charged to the group at the end of the lease.
If you want cover, take your own dated photographs of the vacated room on the day. It has no legal weight, but between flatmates it is almost always enough.
Three decisions to take on announcement day
The exact end date, counted from the registered letter and not from the conversation.
Who looks for the replacement, and the date at which you give up and split the charge between those who stay.
The settlement of advances, written down, with an amount and a date.
Those three take ten minutes. Avoiding them takes three months and costs a friendship.