Density-bonus replacement units: the § 65915(c)(3) gate

Buried in the Density Bonus Law's eligibility subdivision, § 65915(c)(3) conditions every bonus, incentive, concession, waiver and reduced parking ratio on replacement housing when the site has recent residential history. A project that will not replace does not merely lose the bonus — it is ineligible for the whole toolkit, including the waivers that many infill designs depend on.

Because the same standard is cross-referenced by the Housing Crisis Act's demolition rules and several streamlining statutes, the § 65915(c)(3) analysis has become the single replacement calculation most California redevelopment deals run.

• Inventory the five-year history: every dwelling unit on site today plus units vacated or demolished in the preceding five years.
• Classify each unit: (a) deed-restricted affordable; (b) subject to any form of rent or price control; (c) occupied by low or very-low-income households. Any of the three makes it replaceable.
• Match the replacement: equivalent number and bedroom mix, restricted to the same or lower income level, 55-year rental covenants (45 ownership), and located on the project site.
• Income unknown? The statute supplies presumptions tied to HCD/CHAS data — in practice a majority of unknown units land in the low/very-low buckets. Plan on it.

• Underwriting watch-outs:
• Replacement units are in addition to the set-aside that earns the bonus only in the sense that both must be satisfied — a unit can sometimes count for both where income levels align; get the crediting analysis in writing from the city early.
• Rent-controlled units occupied above 80% AMI at withdrawal are replaced at low-income level — the statute's special rule for vacancy-controlled stock.
• Seller data gaps become your problem: demand tenancy files, and price the presumption if they don't exist.

The Housing Crisis Act requires protected-unit replacement "consistent with § 65915(c)(3)" as a condition of demolition approval, and adds relocation and right-of-return duties on top (previous guide). SB 35/423, AB 2011 and SB 9 use kindred screens that simply exclude recently tenanted sites from eligibility rather than allowing replacement — meaning on those paths, a bad tenancy history cannot be cured with replacement units.

• Practical sequencing:
• Screen the site history before choosing the entitlement path — replacement-compatible (density bonus + HCA) vs. exclusion-based (ministerial statutes).
• On mixed sites, the replacement load often decides between a bigger discretionary project and a smaller ministerial one.
• Document the analysis in the application: HCD's Carlsbad letter shows the agency's expectations for how cities must apply the rule.

Replacement units carry restricted rents for 55 years — model them as affordable inventory, not temporarily discounted market units. The load interacts with financing: replacement + set-aside percentages can push a project into 4% LIHTC/bond feasibility (see the financing topic), converting a compliance burden into a capital source. On small sites where the stack exceeds roughly a quarter of units, testing an affordable-financing structure against the market-rate pro forma is usually worth the afternoon.