Tax saving of 11.5% is one off, but the under performance (due to higher expense ratio) is an annual rate. Any tax advantage will be defeated by the higher expense ratio eventually.
Let's make a simple calculation. You start with 1.115 (11.5% tax saving). Multiply it with 0.99 repeatedly (-1% under-performance every year). The tax advantage will be fully offset on the 11th year. From the 12th year onwards, buying IWDA with cash wins.
P/S: Thanks for bringing up this topic. I shelved the idea of using SRS due to its complexity. After some reading, I plan to make use of it to optimize my tax. I also need to read more on CPF hacks and see if it's something I need to make use of by the end of this tax year.
Thanks hwckhs, I was trying to find a way for SRS investment. Please share here if you found better SRS investment .