Raising Cost Basis Through Tax Pairing
Tax pairing means realizing a capital loss and a capital gain as part of one coordinated portfolio plan. If the amounts and tax character align under the capital-gain netting rules, the loss may reduce or eliminate the net gain while the appreciated holding receives a higher basis after repurchase.
Here is a worked example of the mechanics and the limits.
Starting Portfolio
An investor holds two long-term positions:
- Fund A: Value $90,000, basis $60,000, unrealized gain $30,000.
- Fund B: Value $55,000, basis $75,000, unrealized loss $20,000.
The investor wants to reduce Fund A's embedded gain and no longer prefers Fund B's strategy.
Step 1: Harvest the Loss
The investor sells Fund B and realizes a $20,000 long-term capital loss. Before trading, the investor selects a replacement fund that maintains the desired asset-class exposure and reviews purchases across all accounts for wash-sale risk.
The replacement is chosen for investment reasons. Correlation alone does not establish that two funds are or are not substantially identical.
Step 2: Realize an Equal Gain
The investor uses specific-lot identification to sell enough Fund A shares to realize a $20,000 long-term capital gain. Because the sale is at a gain, the wash-sale loss-disallowance rule does not prevent an immediate repurchase of Fund A.
The replacement Fund A shares now have a basis near their current purchase price. The old embedded gain on those shares has been recognized.
Step 3: Apply the Netting Rules
Assuming there are no other capital transactions, the $20,000 long-term loss and $20,000 long-term gain net to zero. Real returns, other trades, carryforwards, and state rules can change the outcome.
The investor has not created wealth from the trade. The investor used the tax value of Fund B's loss to reset basis on part of Fund A.
What Can Go Wrong
- The broker sells the wrong Fund A lot.
- A prior or later purchase creates a wash sale in Fund B.
- The replacement changes the portfolio's risk.
- Trading costs consume the expected benefit.
- Other gains or losses change the tax character.
- The Fund A repurchase starts a new holding period.
The transaction can also affect state taxes, net investment income tax, and income-based thresholds even when the two modeled federal gains and losses are equal.
When the Trade Is Worth Considering
Tax pairing is most defensible when the loss sale and the gain sale each support the portfolio independently. It can be useful for diversification, rebalancing, and reducing a future liquidity problem.
It is weak when the only objective is to make the cost-basis number look higher.
Read the cost-basis strategy primer and use tax-lot optimization before selecting shares.
Bottom Line
Tax pairing can exchange a realized loss for a higher basis in an appreciated holding. Verify lot character, replacement exposure, wash-sale activity, and the complete return before executing.
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