Income is generally apportioned in one of two ways:
- Single-sales factor
- Colorado sourced income of nonresident individuals method
Income is generally apportioned using the single-sales method. When using single-sales method of apportionment, all business income must be apportioned using the single-sales factor. Non-business income may either be directly allocated to the appropriate state or treated as business income, subject to the single-sales factor apportionment. Complete and include Part IV to your return if you are apportioning income using the single-sales factor apportionment method.