The actual ceremony is not, neither is the married life, but the afterlife is.
In the Netherlands we know the fiscal partner. The results of being a fiscal partner is shown in the income tax and inheritance tax aspects. If you are not fiscal partners with your live partner, should you become one?
When you are married, registered partner, have children together, own a house together that is your main residence or mentioned in each others pension arrangement, then you are regarded fiscal partners. However, if you are not married, have no children, do not own a house and have no pension arrangements, you are not regarded tax partners.
Not being tax partners implies you cannot file joint tax returns, you cannot allocate aspects of the tax return to each other, you cannot benefit from the double tax free amount in the wealth tax (Box 3) return. But most important, you cannot use the tax free amounts and low tax rates in the inheritance tax.
If you have EUR 600.000 in assets, you die, then this value goes to your family. If you would like to have this value go to your partner, this needs to be determined in a will and even then not all of the assets go to your partner. The tax free amount is EUR 2.057, the balance being EUR 597.943 is taxed at EUR 227.352. If you would have been a tax partner the amount of the assets fall within the EUR 616.880 tax free amount (2013) an no inheritance tax would have been due.
You could go for the registered partnership, but assuming you being an expat, you have to do this in every country you go to after the Netherlands. So please get married, global solution.