The lease ends when the lease says it ends. Does the lease address whether, if you over stay, is a month to month tenancy created. If so, he could charge you an extra month's rent. However, under no circumstances can he apply the security deposit. Does the landlord have a new tenant coming in or is he just being a jerk? If you stay over one day, I would take the position that you owe him 1/30 th of a month's rent and pay him that, but demand the return of the security deposit. Also, ask him whether he has kept the security deposit in a separate interest-bearing account and ask for proof of the same.
You should move out by August 31 at noon. The fact that the lease purports to end at noon is inconsequential because you are planning to stay until September 1. If you do holdover, the landlord could elect to treat you as a holdover tenant subject to a month-to-month tenancy, and demand rent for the entire month of September. If you don't pay this rent, and then move out, he could withhold this unpaid rent from your security deposit.
I would recommend that you avoid the entire problem and just move out by August 31 at noon. The requirement to leave at noon is odd but you did agree to that term when you signed the lease.
The lease ends when it says, so you should speak to the landlord about a 1 day extension. If a new tenant is moving in, maybe something can be done. However, it would be best to move out when required. While unpaid rent can be withheld from a security deposit, and issue to be addressed is an amount due after the lease ends rent, or payment for use and occupancy. The security deposit law is very strict and if not complied with can be costly for a landlord. Did you get a statement of conditions when you moved in? Did you get proof that the deposit was placed in a separate account in a bank within the Commonwealth?
You may wish to retain an attorney to negotiate this with the landlord, as the landlord may be trying to create a basis to withhold the entire security deposit for the month, and then rent the apartment out right away.
DISCLAIMER: This answer is provided in response to a "hypothetical" question and provided for general, informational purposes and does not create an attorney/client relationship. The information presented is not legal advice and may change based additional information and research. It is recommended that you speak to an attorney to discuss your specific legal issues.
(((NOTE: The following is neither legal advice nor the creation or implication of an attorney-client relationship. It is provided for general informational purposes only.)))
Agreed with the above. Move out by 8/31 at noon. Rent a storage unit and/or get a hotel room if you have to, but if the lease says that's when you must move out, barring some very odd circumstance nullifying the term, that's when you must move out.
Additionally, as my colleague pointed out above, staying past the end-of-lease day/time may create liability for additional rent -- perhaps an additional month or more.
If for some reason you remain unable to move out by the stated time and/or your landlord withholds or continues to threaten to withhold your security deposit, you should contact a local attorney immediately.
Beacon Hill Law