California (CA)
Cal. Civ. Code § 5650(b)(2) — Late charge may not exceed 10% of the delinquent assessment or $10, whichever is greater (unless the declaration sets a smaller amount). Assessments are delinquent 15 days after due unless the declaration allows longer.
Automation can post the fee only after your published grace period and document authority. Payments apply to assessments before late charges (§ 5655).