http://corporate.morningstar.com/US/documents/ResearchPapers/Tracking%20Chinese%20Equity%20ETFs%20May%202014.pdf
缩址:https://goo.gl/hj5YbG
第24页:
Other indices—typically the Net Total Return indices—assume a withholding tax
is paid on dividends, but in practice in certain jurisdictions, either some
portion of or all of this tax can be reclaimed by the ETF’s manager at its
source jurisdiction, provided that there is a branch office in the country
where the tax is levied. This activity, known as tax optimisation or dividend
tax enhancement, can boost a fund’s return relative to its benchmark, but it
can also increase its tracking error.
Both physical and synthetic replication ETFs can be affected by tax
optimisation. In the case of ETFs employing physical replication, this activity
will be carried out at the fund level, directly impacting fund returns, while
in the case of synthetic ETFs, it will be implemented at the level of the
bank(s) standing behind the swap(s) embedded in the fund, thereby indirectly
impacting fund returns. The bank(s) providing the swap(s) can decide whether or
not to pass on any revenues from dividend tax enhancements within the framework
of the swap agreement between the fund manager and the swap providers.

这个只是叙述说有税务优势的一方可以有资产累计优势但是这个计算方式没有指数追踪 且iShare没有详细公布这方面收支 不会知道基金公司到底是把靠税务优势拿到的放到哪边举例来说 假设靠税务拿到0.5%优势 但是ret只有0.25% 剩下的到底在哪里?

反向去算，IWDA换算出来的有效税率在十几％左右。但基金公司有没有吃掉一部分好处很难说。只能说买IWDA不至于真的照30%被课税。