Rebalance in tax-advantaged accounts
Because rebalancing can involve selling assets, it often results in a tax burden—but only if it's done within a taxable account.
Selling these assets within a tax-advantaged account instead won't have any tax impact.
For example, imagine your retirement savings consist of a taxable account and a traditional IRA. Your target bond allocation is 30%, but you've become overweighted in bonds and you need to sell some of them in order to buy stocks and get back into balance.
If you sell bonds from your traditional IRA, there won't be any tax impact. If you sold bonds from your taxable account, on the other hand, you could owe taxes on any gain in the value of the bond since you bought it.