Moving in or out mid-month in Massachusetts? Enter your monthly rent and move-in date to calculate exactly what you owe for a partial month. Updated for 2026.
Prorated rent is the amount you pay when you move in or out on a day other than the first of the month. Instead of paying a full month's rent, you pay only for the days you actually occupy the unit. Most landlords in Massachusetts prorate rent as standard practice, though it is important to confirm the calculation method in your lease before signing.
Massachusetts MGL c.186 §15B caps deposits at 1 month and requires return within 30 days with accrued interest.
The most common method divides your monthly rent by the actual number of days in that month, then multiplies by the number of days you will occupy the unit:
Example: rent is $1,500/month, move-in is the 10th of a 30-day month. Days remaining: 21. Prorated rent: ($1,500 ÷ 30) × 21 = $1,050.
In Massachusetts, the security deposit limit is 1 month's rent. Your landlord must return your deposit within 30 days after move-out with an itemized statement of any deductions. Always document the condition of the unit at move-in and move-out with photos and a written inspection report.
To end a month-to-month tenancy in Massachusetts, either party must provide 30 days' written notice. Your specific lease may require more notice, so always check the lease first. This notice period also affects your final rent calculation if you give notice mid-month.
There are three common ways landlords calculate prorated rent. The actual-days method is most accurate; the 30-day method can benefit tenants in longer months; the 365-day method is more common in commercial leases.
| Method | Formula | Notes |
|---|---|---|
| Actual Days (Standard) | Rent ÷ Days in Month × Days Occupied | Most common; mirrors the actual calendar |
| 30-Day Month | Rent ÷ 30 × Days Occupied | Favors tenant in 31-day months |
| 365-Day Year | (Rent × 12 ÷ 365) × Days Occupied | Common in commercial leases |
There is no statute in Massachusetts mandating a specific proration method. Specify the method in your lease before signing to avoid disputes later.
Massachusetts MGL c.186 §15B caps deposits at 1 month and requires return within 30 days with accrued interest. As a practical matter, most landlords prorate rent voluntarily since it is the standard and fair approach. Confirm the arrangement in writing before signing your lease.
Divide your monthly rent by the number of days in the move-in month, then multiply by the number of days you will occupy the unit. Example: $1,800 rent ÷ 31 days × 15 days occupied = $870.97. Use the calculator at the top of this page for instant results.
In Massachusetts, landlords may collect a security deposit of 1 month's rent. The deposit must be returned within 30 days after you move out, along with a written itemization of any deductions for damages or unpaid rent. Photograph the unit on move-in and move-out to protect your deposit.
In Massachusetts, 30 days' written notice is generally required from either party to terminate a month-to-month tenancy. Many leases specify longer notice periods (commonly 60 days), which take precedence over the statutory minimum. Always review your lease carefully.
Unless a specific statute in Massachusetts requires proration, a landlord is generally not legally obligated to prorate rent. However, it is standard industry practice. If a landlord refuses, negotiate it into the lease as a written term before signing — a written lease provision is enforceable.