If an individual, shareholder or member claims more than one homestead in the same tax year, and has not timely notified the Mayor of all changes in eligibility, the Mayor shall disallow the deduction for all homesteads claimed by the individual, shareholder, or member.
D.C. Code § 47-850.04
Section 3 of D.C. Law 14-147 provided that section 2 shall apply as of October 1, 2001, except insofar as the retroactive application results in an increase of tax to the real property or owner thereof.