俺也认真了，查了一下你们州政府的网站，https://www.mass.gov/renting-in-massachusetts 你们州恐怕有美国对房东最严厉的法，连对租客charge申请费都是非法的，怎么会允许你要application deposit，俺没有在那个网站上看到，却在另一个你州法律援助网站上看到了了这个：
Illegal Fees
When landlords rent apartments to new tenants, sometimes they try to get more money than just the rent. They may try to tack on extra fees such as "holding deposits," "rental fees," "pet fees," or "application fees." These extra charges are illegal. The problem is, if you refuse to pay these fees, a landlord may refuse to allow you to move in.
The only extra charge the law allows is for a rental agent or a real estate broker to charge a "finder's fee." A rental agent can charge a finder's fee only if she is a licensed real estate broker or salesperson. The broker must provide a written notice to prospective tenants with information about the fee and whether or not it is paid if a tenancy is not created. If the rental agent is also the landlord, the law may prohibit her from charging a finder's fee. To find out if a rental agent is a licensed real estate broker, see the Massachusetts Department of Safety license search tool.
https://www.masslegalhelp.org/housing/lt1-chapter-1-what-can-landlord-charge
还是那句话，请拿出你要application deposit 的依据。
