Foreign tax credit carryovers need a history, not just a number.

The general carryback and carryforward rule

For many Form 1116 income categories, excess foreign tax can generally be carried back 1 year and then carried forward 10 years. The excess is applied to the earliest eligible year first. The period is not extended simply because a credit could not be used in an intervening year.

The rule operates within a separate category. Passive category excess follows passive category capacity; general category excess follows general category capacity. Combining unlike categories can overstate the credit and break the reconciliation.

Why foreign tax can go unused

The current-year credit is generally limited in relation to U.S. tax on foreign-source taxable income. A taxpayer can have foreign tax available but too little limitation to use all of it. That can happen when:

• The foreign effective tax rate is higher than the effective U.S. rate on the income.
• Losses or deductions reduce foreign-source taxable income.
• Qualified-dividend or capital-gain adjustments reduce the limitation.
• Income is excluded under Form 2555, with related foreign tax unavailable for credit.
• The timing of foreign income and foreign tax falls in different U.S. tax years.

What Schedule B (Form 1116) does

Schedule B reconciles unused foreign taxes from prior years with current-year use and the amount carried forward. The schedule is completed separately for each applicable income category. It shows the origin year, prior balance, amount used, adjustments, expiration, and ending balance.

How the ordering works

1. Calculate the current-year limitation for the specific category.
2. Apply current-year foreign tax as directed by the Form 1116 rules.
3. Identify excess limitation that can absorb eligible tax from other years.
4. Apply carryovers beginning with the earliest origin year.
5. Remove amounts used, adjusted, or expired and reconcile the ending balance.

A return can therefore use an older carryover while part of a newer amount remains unused. The total ending balance alone does not show which portion will expire first.

Important restrictions

• Section 951A category: the IRS instructions do not allow foreign tax carrybacks or carryovers for this category.
• Credit-without-Form-1116 election: unused tax generally cannot be carried to or from a year for which this election applies.
• Deduction year: a carryback cannot simply be used in a year where foreign taxes were deducted instead of credited without addressing the choice and related rules.
• Category changes: legislation or changes in the character of an item can require special transition or recapture rules.
• Redeterminations: a foreign refund, additional assessment, or other change can revise the historical amount and may require Schedule C.

A simplified carryforward example

Assume a taxpayer has $900 of otherwise eligible passive category foreign tax in 2025 but a 2025 passive category limitation of $650. Ignoring other adjustments, $650 may be used in 2025 and $250 is excess. After testing the prior year for a carryback, any remaining amount may be available in future years through 2035. Each future year still needs passive category excess limitation before that carryforward can be used.

This illustration is deliberately simplified. Real calculations may change for prior carryovers, dividends and gains, taxes not yet creditable, rate conversions, exclusions, or other categories.

What a clean carryover file should contain

• Every Form 1116 for the open 10-year carryforward window, grouped by category.
• Every Schedule B and any worksheets supporting amounts used or expired.
• Amended returns and foreign tax redetermination records.
• A year-by-year ledger that ties to the filed schedules.
• Source documents for the foreign tax and related income.

If a return starts with only a single carryover number and no category or origin-year detail, reconstructing the ledger should come before using that number on a new Form 1116.