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 | Have A Question About This Topic? Address Thank you! Oops! Related Contents 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 Is My Current Net Worth? Use this calculator to estimate your net worth by adding up your assets and subtracting your liabilities.