Trading 212 added the Euronext Brussels (Belgium Stock Exchange) near the close of last Friday (March 26th, 2021).
Does anyone know the withholding rates for Belgium stocks dividends?
Deloitte mentions several withholding tax rates for Belgium stocks dividends for non-residents:
Note: @Team212, a simple suggestion for you to help your customers, create a Help/FAQ page with withholding tax rates for each market present in Trading 212 (at moment it’s only 8 markets).
I have a sneaky feeling it is 30%, perhaps it would make a good thread in the forum for people to update from time to time.
It is probably more difficult than we think, even though its 8 markets, some may differ based on your location.
Most of information I found points to 30%.
Dividend withholding tax
Dividends distributed by a Belgian company to its shareholders are subject to the sole and definitive 30% dividend withholding tax.
The Belgian withholding tax on dividends amounts, in principle, to 30%, subject to reduction or exemption under the applicable Belgian provisions or tax treaties.
Although healthcare real estate (don’t know about other real estate) has a withholding rate of 15%
" However, with effect as from 1 January 2017, a reduced withholding tax of 15% was provided for dividends distributed by a RREC, which invests at least 60% of its real estate directly or indirectly in so-called ‘healthcare real estate’ (new Article 269, §1, 3° of the Belgian Income Tax
Code ‘92)"
I think the divergence on tax rates will be more on which type of income (Dividends, Interest, Royalties) than the investor location (talking about non-residents).
The location will be relevant only for the National Tax Authority and the Double Taxation Agreements between countries.
For brokerages, they received the income net of the withhold tax, made by the payment agent or the brokerage do it according to the income origin.
For example, payment agents/brokerages take 15% on common US stocks (if there is a W8-BEN activated).
For German common stocks, it’s applied a 26,375% withhold tax including surcharge (Current rate of 25% with an additional “solidarity surcharge” of 5.5% of the 25% withheld)
For example, already does it for German stocks dividends (only 7 markets to go 
):
Besides the obvious world beer giant, Anheuser-Busch InBev (a “Beer Pie” or a “Alcohol Pie” or a “Hangover Pie” anyone? 
), there are any other interesting Belgium stocks?
Euronav? KBC Group? I think that value investor will find there some interesting stocks.
It depends, if there is a double taxation avoidance treaty between Belgium and your country of tax residence, this varies. I guess for most EU countries is 15% like for Greek investors. The Belgium-Greek treaty can be found here.
A post from the past. A well-known Belgium company in the past, Agfa:
For those more close to Belgium, any considerations about Agfa?
Performance:
PS: Currently not present in T212.
For those who like Belgian Waffles. 
Who would guess there are also Belgian rockets (present in T212):
I hope that Xior Student Housing will available in T212.
“Based on the number of dividend-entitled shares (158,368,260), the distribution related to the 2020 financial year would correspond to a gross dividend of EUR 2.50 per GBL share (which represents a 20.6% decrease compared to the amount of EUR 3.15 in relation to the 2019 financial year), being equal to EUR 1.75 net per share (it being reminded that the withholding tax rate has been uniformly set at 30% for the GBL dividend since January 1, 2016).”
Some tax considerations on Belgium:
deduction of a liberating withholding tax of 30% when the dividend is paid
This is after the high Belgian withholding tax of 30%, though REITs with at least 60% in care property are only charged 15% (which is important for your (Belgian) tax deduction!).
So a 30% withholding tax for general Stocks and REITs, but REITs with at least 60% in care property is only 15%.
Maybe there are other tax discrimination in Belgian dividends.