MA Sublease – Tenant Signed Lease, Paid First Month, No Move-In Yet, Partial Deposit Only – Can I Terminate?

Hi everyone,

I’m a master tenant in Massachusetts and subleased one bedroom out of 3. Landlord consented to the sublease.

Here’s the situation:

• Fixed-term sublease signed for 6 months.
• Payments due at signing: First month, Last month, and security deposit (less than 1 month).
• Tenant paid the first month only.
• they made only a partial payment toward last month + security.
• The lease start date has technically begun, but I have NOT given keys and have NOT allowed move-in because full required payments were not completed.
• I gave them a written deadline (5th of this month) to complete payment. I have already given multiple chances since last 10 days and they made excuses.

If they fails to pay the remaining balance by the deadline:

1. Can I terminate the lease for failure to complete required payments before possession?
2. Am I required to refund the first month even though I already paid it to my landlord?
3. Can I retain any portion to cover vacancy loss if I have to relist the room? - Although i don't want to keep their deposit and return the last month and security and relist the place for next month. But for current month the deposit is already paid to landlord.
4. Since she never took possession, would this still require a formal eviction process?

I want to handle this correctly under Massachusetts law (MGL c.186 §15B) and avoid violating any security deposit rules.

Appreciate any guidance from MA landlord/tenant folks
Location: Waltham MA