We grouped these two because couples group them, and then found that the answer is genuinely different on each side of the border.
What Seychelles asks you for
The Seychelles half is the same for everyone. Two foreign nationals need a valid passport and an apostilled birth certificate each, plus an apostilled divorce certificate if either has been married before or a death certificate if widowed. The banns run for eleven days. The government fee is SCR 3,000 on Mahe, Praslin or La Digue. Two witnesses must be present and we provide them. The certificate is issued within twenty four hours of the ceremony.
The Netherlands, and the contradiction
A civil marriage concluded under the laws of the country is legally valid in the Netherlands, provided it is not a sham marriage and you are both at least eighteen. That part is not disputed.
What is disputed is registration. The Dutch government position is that residents must register the foreign marriage certificate with their municipality as soon as possible after returning. Several commercial wedding sites say it is optional. Follow the government. It is free, it cannot be done online, and if you live abroad you register in The Hague.
There is also a practical reason to do it regardless of who is right. A foreign extract has limited validity and many Dutch bodies refuse anything older than six months. Once registered, you can request copies from the burgerlijke stand in The Hague forever, which saves both time and money later.
Belgium, and the signature on the signature
Belgium is the strictest chain we found in any market, and the detail that catches people is near the end of it.
The act must be drawn up by the competent foreign authority in the local form, legalised or apostilled, and translated by a sworn translator. Then the sworn translator's own signature must itself be legalised. After that comes recognition by the civil registrar, the drawing up of a Belgian act, and registration in the population, foreigners or waiting register.
Entry in the DABS database is optional but makes obtaining extracts far easier afterwards, and we would take it.
One Belgian risk worth naming
The wetsontduiking provision, evasion of law, is sometimes used to refuse recognition of a foreign marriage act on suspicion of a sham marriage, particularly where there has been an earlier refusal in Belgium. If that is any part of your history, take advice before you book rather than after you marry.
Belgian municipalities also differ on whether registration is compulsory. Check your own commune rather than a national page, because the commune is who you will be standing in front of.