Massachusetts Residential Leasing Guide
Massachusetts Prorated Rent Calculator
Calculate partial-month rent for apartments in Boston, Cambridge, Somerville, Worcester, and across Massachusetts with detailed section-by-section analysis of M.G.L. c. 186, § 15B.
Calculation Breakdown • Generated via QuickProrate.com
Occupancy Type:
Move-In
Effective Date:
-
Base Monthly Rent:
$0.00
Days Occupied:
0 days
Calculation Breakdown
| Calculation Method | Formula Applied | Amount Due |
|---|
Full monthly lease rate
First day tenant possesses property
Prorated Rent Due
for partial month
The 3 Common Calculation Methods
Actual Days in Month
$0.00
Rent ÷ Days in Month
30-Day (Banker's month)
$0.00
Rent ÷ 30 days flat
365-Day Annual Method
$0.00
(Rent × 12 ÷ 365) × Days
Check the rent or proration clause of your lease to see which method applies.
Current Month
Highlighted dates indicate billable occupancy.
Press Ctrl+C / ⌘+C to copy:
Informational tool only, not legal advice. Always follow your signed lease.
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September 10 Move-In: Boston / Cambridge ($2,800/month)
Consider a tenant leasing an apartment in Boston, Cambridge, or Somerville with a monthly rent of $2,800.00 and move-in on September 10th. In September's 30-day duration, the tenant occupies the property for 21 days (September 10 through September 30 inclusive).
| Calculation Method | Daily Rate Formula | Daily Rate | Occupied Days | Prorated Rent Due |
|---|---|---|---|---|
| Actual Days Method30 Days in September | $2,800 ÷ 30 | $93.33 | 21 | $1,960.00 |
| 30-Day Month MethodStandard 30 Divisor | $2,800 ÷ 30 | $93.33 | 21 | $1,960.00 |
| 365-Day Annual Method($2,800 × 12) ÷ 365 | $33,600 ÷ 365 | $92.05 | 21 | $1,933.15 |
September Calendar Note
Because September has exactly 30 days, the actual-days method and 30-day month calculation produce identical results ($1,960.00). In 31-day months (such as October, December, or March), the actual-days method yields a slightly lower daily charge.
Section-by-Section Guide: Massachusetts General Laws Chapter 186, Section 15B
Massachusetts has one of the strictest and most heavily litigated security deposit statutes in the United States. Under M.G.L. c. 186, § 15B, procedural compliance is strictly enforced by Massachusetts Housing Courts, with mandatory treble damages for violations.
1. The "Four Payments Only" Rule: Strict Prohibition on Extra Fees
At or prior to the commencement of any residential tenancy, a Massachusetts landlord is strictly prohibited from demanding or receiving any payments other than the following four items:
1. First Month's Rent
Due at the beginning of the initial tenancy term.
2. Last Month's Rent
At the same monthly rental rate as the first month.
3. Security Deposit
Capped at an amount no greater than one month's rent.
4. Lock and Key Fee
Actual cost of purchasing and installing a new lock and key.
2. Immediate Deposit Receipt & Mandatory 10-Day Statement of Condition
Immediate Move-In Receipt (§ 15B(2)(c)): The landlord must deliver an immediate written receipt upon receiving the security deposit, specifying the exact amount, date received, purpose of payment, name of the person receiving it, and a description of the leased premises.
Written Statement of Condition (§ 15B(2)(b)): Within 10 calendar days after receiving the deposit or the commencement of tenancy (whichever is later), the landlord must provide the tenant with a comprehensive written "Statement of Condition" detailing all existing defects, damage, and sanitary code violations in the unit.
Tenant's 15-Day Review Period: The tenant has 15 calendar days to inspect the apartment, write down any additional damages, sign the document, and return a copy to the landlord. If the landlord fails to furnish the Statement of Condition, they lose the right to withhold any money for repairs at move-out. Use our move-in move-out checklist.
3. Separate Massachusetts Escrow Account, 30-Day Notice & 5% Annual Interest
Escrow Account Segregation (§ 15B(3)(a)): Any security deposit received by a landlord must be held in a separate, interest-bearing escrow account in a bank located within the Commonwealth of Massachusetts. The account must be beyond the claim of creditors of the lessor and cannot be commingled with the landlord's personal or business funds.
30-Day Written Bank Disclosure (§ 15B(3)(a)):
Within 30 calendar days of receiving the security deposit, the landlord must provide the tenant with a written receipt stating:
- The name and address of the bank holding the deposit;
- The specific bank account number; and
- The exact amount deposited.
Failing to deliver this 30-day notice is an incurable violation that entitles the tenant to an immediate return of the entire deposit.
Statutory 5% Annual Interest (§ 15B(3)(b)): If the deposit is held for one year or longer, the tenant is entitled to interest at the rate of 5% per year, or the actual interest rate paid by the bank. The landlord must pay the interest within 30 days after the end of each annual tenancy period, or permit the tenant to deduct it from rent.
4. The 30-Day Return Rule & Sworn Itemized Statements Under Penalty of Perjury
The landlord must return the security deposit plus accrued interest within 30 calendar days after the tenant vacates or the tenancy terminates.
Statutory Requirements for Deductions (§ 15B(4)(iii)):
Deductions are lawful only for unpaid rent, unpaid water usage (if legally submetered under M.G.L. c. 186, § 22), tax escalator charges, and tenant-caused damages beyond reasonable wear and tear.
To make any deduction for physical damages, the landlord must provide an itemized list of damages sworn to by the lessor under the pains and penalties of perjury, accompanied by written evidence such as estimates, contractor bills, invoices, or receipts indicating the actual or estimated cost of repair.
5. Automatic Statutory Forfeiture & Strict Liability Treble Damages (3x Penalty)
Complete Forfeiture of Deductions (§ 15B(6)): The landlord forfeits all right to retain any portion of the security deposit for any reason if they fail to:
- Deposit funds in a separate Massachusetts bank escrow account (§ 15B(3)(a));
- Provide the written 30-day bank disclosure receipt (§ 15B(3)(a));
- Provide a sworn itemized statement of damages with invoices within 30 days (§ 15B(4)); or
- Return the deposit or balance within 30 calendar days of move-out.
Mandatory Treble Damages (§ 15B(7)):
"If the lessor or his agent fails to comply with clause (a), (d), or (e) of subsection 6, the tenant shall be awarded damages in an amount equal to three times the amount of such security deposit or balance thereof to which the tenant is entitled plus interest at the rate of five per cent from the date when such payment became due, together with court costs and reasonable attorney's fees."
Strict Liability Established by Courts: In landmark decisions such as Castenholz v. Caira (21 Mass. App. Ct. 758) and Taylor v. Beaudry (75 Mass. App. Ct. 411), Massachusetts courts held that treble damages are mandatory upon violation. Landlords cannot escape triple liability by returning funds after the 30-day deadline has passed. If your landlord violated § 15B, issue our security deposit return letter.
30-Day Late Fee Grace Period & Month-to-Month Termination Notice
Mandatory 30-Day Late Fee Rule (M.G.L. c. 186, § 15B(1)(c)): Massachusetts law prohibits landlords from imposing any late fee, interest charge, or penalty for late rent until the payment is at least 30 calendar days past due. Any lease provision charging late fees on the 5th or 10th of the month is completely void under state law.
Notice to Terminate Month-to-Month Tenancy (M.G.L. c. 186, § 12): Either party may terminate a periodic month-to-month tenancy at will by providing written notice equal to the interval between regular rent payment dates, or at least 30 calendar days, whichever is longer. Generate your notice using our move-out notice letter.
Local Rental Dynamics: Boston, Cambridge & "Allston Christmas"
Boston & Cambridge (Sept 1)
Driven by over 250,000 university students, more than 70% of residential leases in Greater Boston start on September 1. Mid-month move-ins frequently require actual-day proration.
"Allston Christmas" Turnover
Between August 31 and September 1, massive street turnover occurs in Allston, Brighton, and Mission Hill. Ensure your prorated move-in hours align with truck reservation permits.
Worcester & Pioneer Valley
Worcester, Amherst, and Northampton follow academic turnover schedules. Housing Court specialists strictly enforce M.G.L. c. 186 § 15B escrow rules throughout Central and Western MA.
Massachusetts Proration Frequently Asked Questions
How is prorated rent calculated in Massachusetts?
Massachusetts statutory law does not dictate a mandatory formula for prorating rent. The signed lease agreement determines the calculation method, with most housing providers using the actual number of calendar days in the month, while others utilize a 30-day divisor.
What upfront payments can a Massachusetts landlord legally collect?
Under M.G.L. c. 186, § 15B(1)(b), a landlord may only collect four specific payments at inception: (1) first month's rent, (2) last month's rent, (3) a security deposit not to exceed one month's rent, and (4) the actual cost of a new lock and key. Landlords cannot charge application fees, holding fees, pet fees, or move-in fees.
What is the Statement of Condition requirement under M.G.L. c. 186, § 15B(2)(b)?
Under M.G.L. c. 186, § 15B(2)(b), within 10 days after receiving a security deposit or the commencement of tenancy (whichever is later), the landlord must provide a written Statement of Condition listing all existing damage. The tenant has 15 days to review, amend, sign, and return it.
Where must a Massachusetts landlord hold a security deposit?
Under M.G.L. c. 186, § 15B(3)(a), deposits must be placed in a separate, interest-bearing escrow account in a Massachusetts bank, beyond the reach of the landlord's creditors. Within 30 days of receipt, the landlord must provide a written receipt specifying the bank's name, address, account number, and amount deposited.
What interest must be paid on security deposits in Massachusetts?
Under M.G.L. c. 186, § 15B(3)(b), the tenant is entitled to interest at the rate of 5% per year, or the actual interest rate paid by the bank. Interest must be paid annually within 30 days after the end of each tenancy year, or deducted from the next month's rent.
What are the requirements for damage deductions under M.G.L. c. 186, § 15B(4)?
Under M.G.L. c. 186, § 15B(4), deductions are prohibited for reasonable wear and tear. Deductions require an itemized list of damages sworn to by the landlord under the pains and penalties of perjury, accompanied by written evidence such as estimates, bills, invoices, or paid receipts.
What are treble damages under Massachusetts General Laws c. 186, § 15B(7)?
Under M.G.L. c. 186, § 15B(7), if a landlord fails to place the deposit in a separate MA account, fails to transfer it, or fails to return the deposit within 30 days, the tenant is entitled to three times the amount of the deposit (or balance) plus 5% interest, court costs, and reasonable attorney's fees under strict liability.
When can a Massachusetts landlord charge a late fee?
Under M.G.L. c. 186, § 15B(1)(c), a landlord cannot charge a late fee or penalty until rent is at least 30 calendar days past due. Any lease clause attempting to charge late fees after 5 or 10 days is void and unenforceable under Massachusetts law.
Official Massachusetts Statutes & Legal Sources
- • M.G.L. c. 186, § 15B — Comprehensive Massachusetts security deposit statute (upfront payments, statement of condition, bank escrow, sworn deductions, and treble damages).
- • M.G.L. c. 186, § 12 — Determination of lease at will; 30-day notice to terminate tenancy.
- • M.G.L. c. 186, § 22 — Water and sewer submetering rules and billing standards for residential tenants.
- • Mass.gov Security Deposit Guide — Official Commonwealth of Massachusetts guide for tenants and landlords.
- • State comparison: View all jurisdictions in our Prorated Rent by State Hub.
Legal Disclaimer
This guide provides general educational information regarding Massachusetts landlord-tenant statutes, specifically M.G.L. c. 186, § 15B, and does not constitute formal legal advice. Massachusetts Housing Court interpretations and local housing authorities may enforce specific local rules. If you require legal advice, contact a licensed attorney or a Massachusetts legal aid clinic.