Is there estate tax in Singapore?
TLDR version: While there are no estate tax nor inheritance tax in Singapore, income generated after death from the estate or trust is taxable.
Estate Duty
Estate tax (sometimes also referred to as estate duty) is a tax on the total market value of a person's assets at the time of death. This applies to the overall estate before distributing it. There is also another type of tax known as inheritance tax which taxes on the beneficiaries individually based on what they inherit.
In Singapore, there is no inheritance tax while estate tax has since been removed for those that died on or after 15 Feb 2008. This is regardless of whether the estate is distributed directly in the Will or subsequently in periodic payouts through a testamentary trust.
Example: Testator dies in 2009 leaving $2M, there is no estate tax nor inheritance tax on this amount regardless of distribution method (e.g. if the $2M is given as a lump sum in the Will or distributed via a testamentary trust paying the beneficiary $20k per month for 100 months).
Specifically for property in Singapore, there are also no additional buyer/seller stamp duties for transferring the property to the intended beneficiaries when the testator passed on.
However, do note that there are still applicable fees such as conveyancing fees or other fees that would naturally occur to transfer the name, probate costs, court filing fees, accounting fees which will be paid forth from the Testator's estate.
It is important to take note that some countries do have an estate tax or inheritance tax or both, and this might even differ from state to state within that country. As Tax Planning is another issue altogether, you might want to consider engaging a professional in that country.
Estate/Trust Income Tax
Although there are no estate tax nor inheritance tax in Singapore, any income generated post-death is still subject to income tax. Income tax is payable if the estate or testamentary trust generates income.
When income is generated from an estate or testamentary trust, it can either be taxed at the beneficiary's personal income tax rate if certain conditions are met (e.g. the income was distributed within the same year it was derived etc), or otherwise be taxed at the statutory flat rate of 17% as the income attributed to the Legal Personal Representative (executor or administrator) or that of the trustee.
Example: Testator dies in 2009 leaving behind some assets to a particular beneficiary. Probate was promptly granted to the executor in 2009, and meanwhile those assets generated an additional income of $50k post-death by the end of 2009. In this case, there will be personal tax incurred to the beneficiary in 2009 regardless if the additional $50k income is being paid out as a lump sum through a Will or periodically through a testamentary trust.
Source: Difference Between Estate Duty & Income Tax of An Estate, IRAS website
Source: Estate/Trust Income - What to Declare, IRAS website
If you are interested in the exact details and calculations, you can find out more information on the respective IRAS websites -- Calculating Estate Income Tax, IRAS website & Calculating Trust Income Tax, IRAS website.