of tax imposed under this section with respect to the taxpayer for all prior taxable years, over (2) the sum of— (A) the aggregate credits allowed under sections 25F and 36C with respect to the taxpayer for all prior taxable years, and (B) the aggregate reductions described in subsection (h)(6) with respect to the taxpayer for all prior taxable years. (e) Net unrealized gain (1) In general For purposes of this section, the term net unrealized gain means, with respect to any taxpayer for any taxable year, the excess (if any) of— (A) the aggregate gains which would be recognized if such taxpayer sold each asset held at the close of such taxable year (including any asset described in subsection (c)(3)(A)) for such asset’s estimated value at such time, over (B) the aggregate losses which would be so recognized. (2) Estimated value For purposes of this section— (A) In general Except as otherwise provided in this subsection, the term estimated value means fair market value determined in such manner as the Secretary may provide. (B) Non-readily tradable assets (i) Default method In the absence of regulations or other guidance under clause (iii) or (iv) (and only in such absence), the estimated value of a non-readily tradable asset shall be determined by beginning with the greatest (determined after adjustment under clause (ii)) of— (I) the original basis amount, (II) the adjusted cost basis amount, or (III) the most recent fair market valuation amount. (ii) Adjustment for deemed appreciation Each amount described in subclauses (I), (II), and (III) of clause (i) shall be separately increased by a rate of appreciation equal to the sum of— (I) the annual rate of interest determined by the Secretary to be equivalent to the average of the 5-year constant maturity Treasury yields, as published by the Board of Governors of the Federal Reserve System, for the 5-year period ending on September 30 of the calendar year ending before the date with respect to which the estimated value is determined, plus (II) 2 percentage points,