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Reinvested dividends: are they taxed, and what happens to cost basis?

Yes, reinvested dividends are taxed in a regular account, the same year they're paid, as if you got the cash. Each reinvestment also adds to your cost basis (in Canada, your ACB). Forget that second part and you pay tax on the same money twice.

Beginner guide · 7-minute read · Updated 2026-11-01

The short answer

A reinvested dividend is two things that happen at once:

1. You got paid a dividend. That's taxable income this year, in a regular account.
2. You used it to buy more shares. That's a purchase, and its cost belongs in your Cost basis.

The tax system sees both. You don't get out of the tax by reinvesting. But you also shouldn't be taxed on that money again when you sell. The higher basis is what stops that.

In a US IRA or 401(k), or a Canadian TFSA or RRSP, none of this applies year to year. Dividends aren't taxed inside the account, and you don't track basis there.

How the US and Canada track it

The idea is the same in both countries. The bookkeeping is different.

In the US, each reinvested dividend becomes its own small lot. It has its own purchase date, so its own holding period. In Canada, every share of the same company in your regular accounts is averaged into one Adjusted cost base.

A worked example where the price falls (hypothetical)

You buy 100 shares of a made-up company at $40, for $4,000. It pays $0.40 a share every quarter, and you reinvest. For round numbers, each dividend buys exactly one share.

You paid tax on $162.40 of dividends that year, even though no cash reached you.

Your correct basis is now $4,000 + $162.40 = $4,162.40, on 104 shares. In Canada, that's an ACB of about $40.02 a share ($4,162.40 ÷ 104).

Then the business stumbles and the stock falls to $36. You sell all 104 shares for 104 × $36 = $3,744.

The double-tax mistake, in numbers

Here's what you report if you add the reinvested dividends to basis, and what you report if you forget.

Check the gap a second way. The two losses differ by $418.40 − $256.00 = $162.40. That's exactly the dividends you reinvested. So forgetting them throws away $162.40 of loss you were owed.

You lost real money on this stock. Your shares fell from about $40 to $36. The mistake makes your tax return say you lost less than you did. You paid tax on the dividends when they came in. Then you paid again by shrinking your loss.

If the price had risen instead, the mistake would show a bigger gain than the real one. Same $162.40, taxed twice either way.

Why this mistake is so common

• No cash moved. It doesn't feel like a purchase, so people don't record it.
• Old shares, moved accounts. When shares move between brokers, basis records sometimes don't come along.
• Canada leaves it to you. Your broker's book value can be wrong for CRA purposes, especially if you hold the same stock at two brokers.
• Many small buys. Four a year for ten years is 40 small purchases. Nobody remembers those by memory.

What to do about it

• Keep a simple log. Date, shares bought, price, dividend amount. One line per reinvestment. A spreadsheet is enough.
• US investors: check that your broker's basis report includes the reinvested lots. Look at the 1099-B when you sell.
• Canadian investors: keep your own ACB running total. Add each reinvestment, divide by the new share count. Our synthetic DRIP guide walks through a year of it.
• Know your dividend's tax type. US readers, see qualified dividend tax rates for 2026. Canadian readers, see the dividend tax credit.

Holding period note for US investors: each reinvested lot starts its own clock. A lot bought last month is short-term if you sell it now, even if the rest is years old.

As of October 2026, the IRS covers basis in Publication 550 and the CRA covers ACB on canada.ca. Check them the year you sell.

Should you reinvest at all? That's its own question: DRIP vs taking dividends in cash. For the full picture, read dividend investing explained. If you sell covered calls on the same shares, the premiums have their own rules, covered in the wheel strategy.

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