Tax-Loss Harvesting Before December 31, Without a Wash Sale

The first time I tried tax-loss harvesting, I sold a losing fund on December 9, felt clever for about three weeks, and then found out in February that the loss had been partly disallowed. My brokerage had reinvested a quarterly dividend into the same fund on December 20. That one automatic purchase of 4.2 shares was enough to trigger the wash sale rule on part of my sale, and the 1099-B said so in a column I had never looked at before.

That is the real problem with harvesting losses in a small taxable account. The idea is simple and widely repeated. The mechanics are where ordinary investors lose the benefit, usually through something automatic they forgot was switched on. This piece walks through how I do it now, with the numbers from my own account, before the December 31 deadline.

What a harvested loss actually buys you

When you sell an investment in a taxable brokerage account for less than you paid, you realize a capital loss. That loss first cancels out capital gains you realized during the same year. Short-term losses offset short-term gains first, long-term losses offset long-term gains first, and then whatever is left crosses over.

If your losses are larger than your gains, you can deduct up to $3,000 of the excess against ordinary income such as wages ($1,500 if married filing separately). Anything beyond that carries forward to future years with no expiration. You do not lose it. You just use it later.

Here is what that looked like for me last year. I had $1,140 in realized long-term gains from rebalancing out of a bond fund. I harvested $4,920 in losses from an international index fund I had bought in early 2022. The first $1,140 of losses erased those gains. The next $3,000 reduced my taxable wages. The remaining $780 rolled into this year. In my 22 percent bracket, the $3,000 wage offset alone was worth $660 in federal tax, plus a little at the state level.

None of this works inside an IRA or a 401(k). Those accounts are already sheltered, so a loss there has no tax value at all. If you are not sure which kind of account you have, start with how a brokerage account differs from a retirement account.

The wash sale rule, explained by the ways it catches people

The rule says you cannot claim a loss on a sale if you buy the same or a "substantially identical" security within 30 days before or 30 days after the sale. That is a 61-day window centered on the sale date. The loss is not destroyed. It gets added to the cost basis of the replacement shares, so you recover it eventually when you sell those. But it will not help this year's return, which was the entire point.

The definition is short. The traps are not. These are the four I have either hit or watched a friend hit:

• Dividend reinvestment. If the fund you sold pays a dividend within 30 days and reinvestment is on, that small purchase creates a partial wash sale. Turn off reinvestment for that holding at least a month before you sell.
• Buying in your IRA. The IRS position, from Revenue Ruling 2008-5, is that buying the same fund in your own IRA within the window disallows the loss, and in that case the basis adjustment does not help you, because IRA basis does not work the same way. That loss is effectively gone.
• Your spouse's account. Purchases by a spouse count as yours for this rule. My partner's automatic monthly contribution once bought the exact fund I had just sold.
• A second brokerage. Your broker only tracks wash sales for identical securities inside the same account. If you sell at one firm and buy at another, the 1099-B will not flag it, and the responsibility for reporting the adjustment is yours.

"Just buy it back in 31 days" is weaker advice than it sounds

The standard tip is to sell, wait 31 days, and buy the same fund back. That avoids the wash sale. It also leaves you out of the market for a month, and in my experience that month is not neutral.

In December 2023, I sold a total market fund to harvest a loss of roughly $1,600 and sat in cash for 31 days. The fund rose about 4.5 percent over that stretch. On the roughly $19,000 I had pulled out, I missed around $850 of growth to save perhaps $350 in tax. I would not call that a disaster, but it was a bad trade, and it was the trade the popular advice told me to make.

What I do now is swap into a similar fund that tracks a different index on the same day I sell. Selling an S&P 500 fund and buying a total US market fund keeps nearly the same exposure, because the 500 largest companies make up most of the total market by weight. The IRS has never published a precise test for "substantially identical," so I will not tell you this is guaranteed safe. What I can say is that funds tracking different indexes from different providers are the swap most tax professionals I have read consider reasonable, while switching between two S&P 500 funds from different companies is the gray area I personally avoid.

The goal is to change the ticker and the index while keeping almost the same exposure, not to sit in cash and hope the month is flat.

A timeline that finishes before December 31

Losses count in the tax year the trade is executed, so a sale on December 31 counts for this year. I still do not leave it that late. Markets close early around the holidays, and a sell order that fills on the morning of January 2 belongs to next year's return. My working calendar looks like this:

1. By mid-November, open your brokerage's unrealized gain and loss page and sort by loss. Note only positions where the loss is large enough to matter after any trading costs. For me that threshold is around $500.
2. For each candidate, turn off dividend reinvestment and check whether a dividend is scheduled in the next 30 days. Many index funds pay in late December, which is exactly when people harvest.
3. Check your IRA, your spouse's accounts, and any automatic investments for purchases of the same fund since late October. Pause anything that would buy it before late January.
4. Pick the replacement fund before you sell. Write down its ticker and the index it follows.
5. Sell and buy on the same day, ideally in the first or second week of December. Save the trade confirmations.
6. Put a reminder on your calendar 31 days later before you switch back, if you plan to switch back at all. Often I do not, because the replacement fund is fine to keep.

When your 1099-B arrives in February, check the wash sale column. If it shows anything, find the purchase that caused it. Your return will list each sale on Form 8949 and total them on Schedule D, and a tax program will carry those numbers through, but it only knows what the 1099-B tells it.

When harvesting is not worth the effort

Harvesting lowers your cost basis, which means a larger gain later when you sell the replacement. You are deferring tax, not erasing it, unless you hold until death, donate shares, or sell in a year when your income is low enough for a 0 percent long-term rate. If you are in the 10 or 12 percent bracket now and expect higher income later, a harvested loss today could cost you more in the future than it saves.

It is also not worth it on a $200 loss. Between the paperwork and the risk of a mistake, I skip anything small. If your withholding or estimated payments already have you close to even, the extra $3,000 deduction may simply grow your refund, and the way withholding shapes your refund is worth understanding before you count on that money. More on filing basics sits in the taxes section.

Do this before Friday

Log in to your taxable brokerage account and find the dividend reinvestment setting for any fund currently showing a loss. Turn it off for those funds only. That single change protects a December sale from the mistake that cost me part of my first harvest, and it takes about five minutes.