两句话不理解：

The accrual equivalent after-tax return moves closer to the pre-tax return as the time horizon increases because the value of tax deferral increases with time.

The accrual equivalent after-tax return also moves closer to the pre-tax return as more of the portfolio return is deferred because the portfolio earns compound interest tax-free.

who can explain them for me? thank you!

1 求FVIF(TAXABLE)对TIME的偏导数,结果是大于0的,说明"increases"   但FVIF(TAXABLE)上界是pre-tax return对应的FVIF

2极端情况:全部是"deferred",必然比部分是"deferred"的RETURN更接近pre-tax return