Section 1000.306 - How can the IHBG formula be modified?(a) The IHBG formula can be modified upon development of a set of measurable and verifiable data directly related to Indian and Alaska Native housing need. Any data set developed shall be compiled with the consultation and involvement of Indian tribes and examined and/or implemented not later than 5 years from the date of issuance of these regulations and periodically thereafter.(b) The IHBG Formula shall be reviewed not later than May 21, 2012 to determine if a subsidy is needed to operate and maintain NAHASDA units or if any other changes are needed in respect to funding under the Formula Current Assisted Stock component of the formula.63 FR 12349, Mar. 12, 1998, as amended at 72 FR 20024 , Apr. 20, 2007; 81 FR 83680 , Nov. 22, 2016