If the dividends arrive in USD and you have Manual FX for USD activated, no conversion has to be performed at all. Therefore the fees of AutoFX are irrelevant for this case.
If you don’t activate Manual FX, you pay 0.5 % when you receive dividends and 0.5 % when you reinvest them in a foreign currency. So, you may lose 0.5-1 % using AutoFX.
General calculation for investing in a foreign currency on DeGiro
If you want to know if you should activate Manual FX in DeGiro for any kind of investment, the formula goes like this:
Break-even point for AutoFX vs Manual FX:
0.5% * x = 0.25% * x + 10 €
If you do the maths, you get 4000 € (price is in € in DeGiro’s price list).
So, you’d need roughly 4000 Euro worth per transaction in a foreign currency (i.e. a currency different from your account’s base currency) to make activating manual FX worthwhile.
Caveats:
- You can open a DeGiro account in a different base currency than CHF, but I don’t know how if it’s possible to transfer USD or EUR in.
- Make sure you take in consideration the spreads and trading cost when investing in a different currency. Investing in an ETF on SWX in CHF may save you the currency conversion, but depending on the spread it might still not be worthwhile to do so.