Just to clarify, the title says international bond, but the post refers to international stock. The answer will be very different.
For ideal tax efficiency. Follow these steps in order.
1. Put bonds in pre-tax accounts(IRAs, 401ks, 403b, etc.) first, Roth second, taxable last. (If you put bonds in taxable consider taxable VS tax free bonds.)
2. Put domestic stock index funds in taxable first, Roth second, Pre-tax last.
3. Put most aggressive index funds(normally international and/or small caps) in Roth 1st, taxable second, pre-tax last.
4. For active mutual funds, don't use them. If you do, try to put in pre-tax if it's a more conservative investment or Roth if it's more aggressive. Never put active funds in a taxable account. If the taxable account is the only space available then you should use index funds instead.
These steps do overlap, but if you follow them in order you will end up with your bonds and domestic stock index funds in their most tax efficient locations and then using left over investments to fill in the gaps.
Example 1. 50/50 portfolio, 100k pretax, 50k taxable. Pre-tax= 75k in bond funds, 25k in international stock index funds. Taxable = 45k in domestic stock index fund, 5k in international stock index fund.
Example 2. 50/50 portfolio, 100k pretax, 50k taxable, 50k Roth. Pre-tax = 100k in bond funds. Taxable = 50k in domestic stock index funds. Roth = 10k in domestic stock index funds, 40k in international stock index fund.
To answer your direct question about international stocks, refer to step 3. If your Roth still has room after handling bonds then you would put the international stocks there. If your taxable account still has room in it after your domestic stocks are taken care of, then you would the international stocks there. Since international stocks are step 3, then where you put them will depend heavily on where you put the other investments. Now yes, if you put international stocks in a taxable account you will get some tax credits but the international stock dividends are less likely to be qualified than domestic stock dividends. I wouldn't let that drive my decision though because domestic stock index funds will normally be even more tax efficient, and bond funds will be less tax efficient so worry about those before deciding what to do with your international stock funds.
