The California Form 3521, known as the Low-Income Housing Credit form, is a crucial document for taxpayers involved in low-income housing projects in California. This form must be attached to the California tax return and is designed to assist taxpayers in calculating their available low-income housing credits for the tax year. It requires essential information such as the taxpayer's name, Social Security Number (SSN) or Individual Taxpayer Identification Number (ITIN), and building identification numbers (BINs) for the properties in question. The form also includes sections to determine any changes in the eligible basis of the property since the last allocation, current year credits, and any affiliated credits from other entities. Taxpayers must report their current year credit, including any amounts from passive activities and carryovers from previous years. Additionally, if there has been a decrease in the eligible basis of a project, the form provides a dedicated section for recalculating the basis. Overall, the California Form 3521 is a comprehensive tool that ensures taxpayers accurately claim their low-income housing credits while complying with state tax regulations.