Reviewed September 2026.
Rebalancing restores your target mix after markets move weights. The tax surprise is almost always a taxable brokerage sale that realizes a large capital gain when you could have fixed drift with new cash or an IRA trade instead. Calendar and band rules live in Rebalancing a portfolio and Rebalancing bands. This page is the account-order playbook so the fix does not create an April bill you did not plan.
Prefer this order (cheapest tax friction first)
- New contributions to the underweight sleeve (401(k), IRA, or taxable buys).
- Dividends and interest directed to the underweight sleeve instead of buying more of what already ran.
- Trades inside tax-advantaged accounts (traditional/Roth IRA, 401(k)): sell overweight, buy underweight with no immediate capital-gains tax on the trade itself.
- Taxable sales last, preferring long-term lots and smallest gains needed to finish the job.
Wrappers overview: Taxable vs tax-advantaged accounts. Pick the target mix first with Asset allocation basics.
Taxable vs IRA: same drift, different bill
| Fix method | IRA / 401(k) | Taxable brokerage |
|---|---|---|
| Sell $4,000 stock fund, buy bonds | Usually no capital-gains tax on the trade | May realize gain on the sold shares |
| Add $4,000 new cash to bonds | Fine | Often best first move |
| Do nothing at 2-point drift | Fine | Often fine; wait for cash or next band breach |
Worked example: 70/30 drifts to 78/22
Riley’s household target is 70% stocks / 30% bonds. After a strong equity year:
| Sleeve | Target $ (on $100k) | Actual | Drift |
|---|---|---|---|
| Stocks | $70,000 | $78,000 | +8 pts |
| Bonds | $30,000 | $22,000 | −8 pts |
| Total | $100,000 | $100,000 |
Riley needs about $8,000 more in bonds (or less in stocks) to restore 70/30.
Path A (IRA-heavy): $60k of the portfolio sits in a Schwab IRA. Riley sells $8,000 of the stock index inside the IRA and buys the bond index. No Form 1099-B capital-gain line from that trade.
Path B (taxable contribution-only): Selling $8,000 of stock fund with a $3,000 embedded long-term gain could add ~$3,000 to taxable income. At a 15% LTCG rate (illustrative), federal tax ≈ $450, plus any state tax. To restore 70/30 without selling, stocks stay at $78,000, so total must rise to $78,000 ÷ 0.70 ≈ $111,430. Bonds need ≈ $33,430; Riley already has $22,000, so about $11,430 of new bond contributions (roughly $950/month for 12 months) finishes the job with no realized gain.
Path C (mixed): Sell $4,000 of stock inside the IRA; put the next $4,000 of taxable contributions into bonds. Drift closes faster without a large taxable sale.
Taxable sale hygiene (when you must sell)
- Prefer long-term lots (held >1 year) over short-term lots taxed as ordinary income (Holding periods).
- Sell the lot with the smallest gain (or a loss you intended to harvest) that still fixes the band.
- Wash-sale window: purchases of a substantially identical security within 30 days before or after a loss sale can disallow the loss, including automatic dividend reinvestment and a purchase in an IRA across accounts. Check the full window before you combine a taxable loss sale with an IRA buy of the same fund. Harvesting overview: Tax-loss harvesting basics.
- Estimate the gain before you click sell; check cost basis in the broker’s tax lot screen.
Checklist
- Confirm target weights in writing (example: 70/30).
- Measure drift; act on a 5-point band or a twice-yearly calendar, not daily noise.
- Try contribution and dividend routing first.
- Rebalance inside IRA/401(k) before taxable sales.
- If selling taxable shares, estimate LTCG/STCG and keep the trade as small as the band requires.
- Save trade confirms for tax software.
Educational only. Not tax or investment advice. Capital gains rates, wash-sale rules, and plan trading policies change; confirm with IRS.gov and your custodian.