Principles of Preserving Wealth The slideshow presentation that you would like to view is too large for your current screen resolution. Click here to view to view the slideshow at full resolution. Launch Presentation » Share | Related Content When Do You Need a Will? When do you need a will? The answer is easy: Right Now. Put It in a Letter A letter of instruction provides additional and more personal information regarding your estate. What's My Potential Estate Tax? This calculator helps estimate your federal estate tax liability.