Assessments of any deficiencies in the tax due under this chapter, or any interest and penalties thereon, shall be governed by § 47-4312. The Mayor may determine the gross income, adjusted gross income, and any itemized deductions necessary to arrive at the taxpayer's proper taxable income. Any assessment made or proposed on the basis of such determinations shall be deemed prima facie correct. Any assessment, compromise, closing agreement, settlement, adjustment, ruling, or other determination of the individual's, estate's, or trust's income or status for federal income tax purposes made or proposed by the Internal Revenue Service, or other competent federal authority, shall not be binding or deemed controlling on the Mayor, the courts, or such taxpayers in determining their taxable income for District income and franchise tax purposes.
D.C. Code § 47-1812.05
Notice of deficiency is different from an assessment: This section obviously contemplates that an assessment is to be made after the notice of deficiency has been issued, after the taxpayer has filed a protest, and after any hearing has been held.
Documentary evidence, certified mail return receipts, see § 14-506. .