GQ, @Nullo.
The short answer is “yes”, you do have to declare as income dividends received in a non-tax-deferred account even when those dividends are immediately reinvested in the stock that produces them.
Here’s my source for that information.
4)Do I have to pay tax on reinvested dividends?
Dividend reinvestment plans let you choose to use your dividends to buy (through an agent) more shares of stock in the corporation instead of receiving the dividends in cash. If you are a member of this type of plan and use your dividends to buy more stock at a price equal to its fair market value, you must report the dividends as income. If you are a member of a dividend reinvestment plan that lets you buy more stock at a price less than its fair market value, you must report as income the fair market value of the additional stock on the dividend payment date. Other rules may apply. For additional information, refer to Chapter 9 of Publication 17, Your Federal Income Tax, and Tax Topic 404, Dividends.
If your ownership is in a tax-deferred account such as a 401(k) or IRA, then no dividends need to be declared when the income (or reinvestment) occurs within the tax-deferred account. I know that much because of my own experience of owning an IRA and reinvesting dividends since IRAs were first introduced.
But my question for you (after a final review of your question) is: Why are you filling out a 1099? The form 1099 is issued to you as an income recipient in order to provide supporting documentation for your own tax return. Unless you’re the one paying the dividend, you should not be “filling out” a 1099.