44 C.F.R. § 61.11
Effective date and time of coverage under the Standard Flood Insurance Policy—New Business Applications and Endorsements
(a) During the 13-month period beginning on the effective date of a revised Flood Hazard Boundary Map or Flood Insurance Rate Map for a community, the effective date and time of any initial flood insurance coverage shall be 12:01 a.m. (local time) on the first calendar day after the application date and the presentment of payment of premium; for example, a flood insurance policy applied for with the payment of the premium on May 1 will become effective at 12:01 a.m. on May 2.
(b) Where the initial purchase of flood insurance is in connection with the making, increasing, extension, or renewal of a loan, the coverage with respect to the property which is the subject of the loan shall be effective as of the time of the loan closing, provided the written request for the coverage is received by the NFIP and the flood insurance policy is applied for and the presentment of payment of premium is made at or prior to the loan closing.
(c) Where the following conditions are met, the effective date and time of any initial purchase of flood insurance coverage for any privately-owned property will be 12:01 a.m. (local time) on the first calendar day after the application date and the presentment of payment of premium:
(1) The Administrator has determined that the property is affected by flooding on Federal land that is a result of, or is exacerbated by, post-wildfire conditions, after consultation with an authorized employee of the Federal agency that has jurisdiction of the land on which the wildfire that caused the post-wildfire conditions occurred; and
(2) The flood insurance coverage was purchased not later than 60 calendar days after the fire containment date, as determined by the appropriate Federal employee, relating to the wildfire that caused the post-wildfire conditions described in clause (1).
(d) Except as provided by paragraphs (a), (b), and (c) of this section, the effective date and time of any new policy, added coverage, or increase in the amount of coverage will be 12:01 a.m. (local time) on the 30th calendar day after the application date and the presentment of payment of premium; for example, a flood insurance policy applied for with the payment of the premium on May 1 will become effective at 12:01 a.m. on May 31.
(e) Adding new coverage or increasing the amount of coverage in force is permitted during the term of any policy, subject to any applicable waiting periods. The additional premium for any new coverage or increase in the amount of coverage will be calculated pro rata in accordance with the rates currently in force.
(f) With respect to any submission of an application in connection with new business, the payment by an insured to an agent or the issuance of premium payment by the agent does not constitute payment to the NFIP. Therefore, it is important that an application for flood insurance, as well as the full amount due, be mailed to the NFIP promptly in order to have the effective date of the coverage based on the application date plus the waiting period. If the application and the full amount due are received at the office of the NFIP within ten (10) calendar days from the date of application, the waiting period will be calculated from the date of application. Also, as an alternative, in those cases where the application and premium payment are mailed by certified mail within four (4) calendar days from the date of application, the waiting period will be calculated from the date of application even though the application and full amount due are received at the office of the NFIP after ten (10) calendar days following the date of application. Thus, if the application and premium payment are received after ten (10) calendar days from the date of the application or are not mailed by certified mail within four (4) calendar days from the date of application, the waiting period will be calculated from the date of receipt at the office of the NFIP. To determine the effective date of any coverage added by endorsement to a flood insurance policy already in effect, substitute the term endorsement for the term application in this paragraph (f).
(g) The rules set forth in paragraphs (a) through (f) of this section apply to Write Your Own (WYO) companies, except that agents must mail the premium payments and accompanying applications and endorsements to the WYO company and the WYO company must receive the applications and endorsements, rather than the NFIP.