How do you prorate rent for a mid-month move-in?
Divide the monthly rent by the number of days in that month, then multiply by the days the tenant will live there, counting move-in day. A second method divides a year of rent by 365 to get one daily rate for every month. Pick one method, write it into the lease, and use it for every tenant.
The two common methods
| Method | Daily rate | Good to know |
|---|---|---|
| Days in the month | Monthly rent divided by the days in that month (28 to 31) | Simple to explain. The daily rate changes month to month, so February days cost more. |
| Yearly daily rate | Monthly rent times 12, divided by 365 | Same daily rate all year. A little lower than the first method in short months. |
Both are fair if the lease says which one you use. The difference is usually a few dollars, though it grows in February. Count the move-in day as a paid day: a tenant who gets keys on the 18th of a 30-day month pays for 13 days (the 18th through the 30th).
Worked example: a September move-in
Example a made-up unit rents for $1,450 a month. The tenant moves in on September 18. September has 30 days, so the tenant is there 13 days. Days in the month method: $1,450 divided by 30 is $48.33 a day, and $1,450 times 13 divided by 30 is $628.33. Yearly daily rate method: $1,450 times 12 is $17,400, divided by 365 is $47.67 a day, and $17,400 times 13 divided by 365 is $619.73. The two methods differ by $8.60.
Round only at the end. Multiplying a rounded daily rate by the days can leave you a few cents off, which matters when you match payments by exact amount.
Worked example: a February move-in
Example a made-up unit at the same $1,450 rent gets a tenant on February 20 in a year when February has 28 days. The tenant is there 9 days. Days in the month method: $1,450 times 9 divided by 28 is $466.07. Yearly daily rate method: $17,400 times 9 divided by 365 is $429.04. Here the methods differ by $37.03, because February is short.
If you use the days in the month method, a tenant moving in late February pays a higher daily rate than one moving in late March. That is allowed when the lease says so, but explain it at signing so it does not look like a mistake.
What to collect at move-in
Many owners collect the prorated amount plus the first full month together, so that from then on rent is due on the 1st like every other unit. Others collect only the prorated amount at move-in and the full month on the 1st. Either way, state it in the lease and in the move-in letter.
Some states cap what you may collect before a tenancy starts. In Massachusetts, General Laws chapter 186, section 15B limits it to the first month's rent, the last month's rent at the same rate, a security deposit of up to one month's rent, and the cost of buying and installing a new lock and key. Check your own state before you add other move-in charges.
Example a made-up tenant signs for a $1,450 unit starting September 18 and the owner collects the prorated September amount with October's rent. Using the days in the month method, the first payment is $628.33 plus $1,450, or $2,078.33, plus whatever deposit the lease and state law allow.
Prorating at move-out
The same math works in reverse when a tenancy ends mid-month by agreement, but read your lease and state law first. Many leases require a full month's notice and rent through the end of the notice period, and some states set their own rules for how a tenancy ends. Do not refund a partial month unless the lease or the law calls for it, and if you do, use the same method you used at move-in.
Lease wording that prevents disputes
- Name the method: "Rent for a partial month is the monthly rent divided by the number of days in that month, times the number of days the tenant has possession, including the first day."
- Say when the prorated amount is due and whether it is paid with the first full month.
- Show the calculation on the move-in statement, with the daily rate and the number of days.
- Use the same method for every unit in the building.
How DoorKeeping handles it
You can ask your AI app, connected to DoorKeeping, to work out a prorated first month and show the math before anything is charged. The tenant pays your own bank directly, with a memo and an exact amount, and DoorKeeping records it in that property's books. Every amount waits for your one-tap approval.
Sources
- Massachusetts General Laws chapter 186, section 15B, read Oct 29, 2026
Questions
- Do you count the move-in day when prorating rent?
- Usually yes. The tenant has the unit that day, so a move-in on the 18th of a 30-day month is 13 days. Say so in the lease.
- Should I divide by 30 or by the actual days in the month?
- Either is common if the lease says which. Dividing by the actual days is easiest to explain; a yearly rate of monthly rent times 12 divided by 365 keeps the daily rate the same all year.
- Can a tenant refuse to pay prorated rent?
- If the lease starts mid-month and sets the prorated amount or method, it is rent owed for those days like any other rent.