24 C.F.R. § 886.311a

(a) The Contract will provide that the owner will notify each assisted family, at least 90 days before the end of the Contract term, of any increase in the amount the family will be required to pay as rent which may occur as a result of its expiration. If the Contract is to be renewed but with a reduction in the number of units covered by it, this notice shall be given to each family who will no longer be assisted under the Contract.

(b) The notice provided for in paragraph (a) of this section shall be accomplished by: (1) Sending a letter by first class mail, properly stamped and addressed, to the family at its address at the project, with a proper return address, and (2) serving a copy of the notice on any adult person answering the door at the leased dwelling unit, or if no adult responds, by placing the notice under or through the door, if possible, or else by affixing the notice to the door. Service shall not be considered to be effective until both required notices have been accomplished. The date on which the notice shall be considered to be received by the family shall be the date on which the owner mails the first class letter provided for in this paragraph, or the date on which the notice provided for in this paragraph is properly given, whichever is later.

(c) The notice shall advise each affected family that, after the expiration date of the Contract, the family will be required to bear the entire cost of the rent and that the owner will be free (to the extent the project is not otherwise regulated by HUD) to alter the rent without HUD approval, but subject to any applicable requirements or restrictions under the lease or under State or local law. The notice shall also state:

(1) The actual (if known) or the estimated rent which will be charged following the expiration of the Contract;

(2) The difference between the rent and the Total Tenant Payment toward rent under the Contract; and

(3) The date the Contract will expire.

(d) The owner shall give HUD a certification that families have been notified in accordance with this section with an example of the text of the notice attached.

(e) This section shall apply to (1) Contracts involving Substantial Rehabilitation entered into pursuant to Agreements executed on or after October 1, 1981, or Contracts involving Substantial Rehabilitation entered into pursuant to Agreements executed before October 1, 1981, but renewed or amended on or after October 1, 1984 and (2) all other Contracts executed, renewed or amended on or after October 1, 1984.