Investors do have to report dividends as taxable income even if they reinvest them to buy more shares. Companies and brokerage companies will report such dividends on 1099-DIV forms the same way regardless of whether you reinvest in new shares, and the IRS will expect you to include them on your annual tax return. You should receive a 1099-DIV for the stocks that are in the dividend reinvestment program.
Stocks (Options, Splits, Traders) 2 | Internal Revenue Service (irs.gov)
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