Your spouse's net income for the tax year is required to calculate certain spousal credits when filing a joint return. If you choose to prepare your returns together, TurboTax can automatically optimize credits and deductions between you.
Most spousal amounts don’t apply if your spouse’s net income exceeds approximately $15,000. So if you're preparing your returns separately (and one of you has a net income close to, or under, $15,000), you should prepare the return of that person first.
If you’re confident your spouse’s income is well above $15,000, enter an estimate of their income, but be aware that certain amounts, such as childcare expenses, must be reported on the return of the person with the lower income.