I provided 6 week notice prior to moving out, when only a month was required. Now my landlord is challenging my move out date.

I assume : (a) that this was a residential tenancy. (The rules are different, at least as to the security deposit, if it was not a residence.)

(b) that you were a tenant at will (different rules apply if you were a tenant under a lease)

If both assumptions are correct then the applicable statute (MGL c. 186, s. 12) requires that the 30 day notice (so-called) be in writing to be effective.

You should speak with an attorney, however, as there are other possibilities. For instance:
(1) if the landlord accepted your surrender of the premises that should start the running of the time within which the landlord must return your security deposit or the balance to which you are entitled. Acceptance of surrender will terminate the tenancy even if though the notice did not meet the requirements of the statute.
(2) if the landlord did not comply with certain provisions of the security deposit law the landlord forfeits all right to retain any part of the security deposit for any reason.
(3) it may be that the facts support the conclusion that the tenancy was otherwise terminated by the actions of the parties, such as any discussions you may have had with the landlord. (If so the date of termination will determine the obligations of the landlord to return the security deposit or otherwise comply with the security deposit statute.)

They may be other possibilities which an attorney familiar with this area of the law will see after an opportunity to develop the facts more.

Good Luck in your claim.

Daniel T. Blake

This response and the information contained herein are not intended to form an attorney-client relationship. The answer provided is based solely on the few facts presented in the question and represents at most a preliminary and hypothetical response. It is for informational purposes only and may not be considered as legal advice. For specific legal advice and recommendations about your particular situation, contact an attorney to schedule a consultation