The county fee schedule alone already creates a substantial baseline.

The FY 2025-2026 fee guide from County of San Diego lists:

• Tentative Parcel Map Condo Conversion: $15,530
• Parcel Map Review: $5,946

That’s over $21,000 before you’ve hired a surveyor or attorney.

Official fee guide:

San Diego County PDS Fee Schedule

And that’s why homeowners who think they’re spending “a few thousand for paperwork” get wrecked halfway through planning.

What Is a Condominium Plan?

This is the document that legally defines your ADU as a separate sellable property.

It is not a sketch.

It is a professionally prepared subdivision document that defines:

• Unit boundaries
• Airspace
• Common areas
• Easements
• Access rights
• Utility pathways
• Shared maintenance responsibilities

A licensed surveyor or civil engineer prepares it.

That survey work alone can easily exceed $20,000 in San Diego.

Why so expensive?

Because the surveyor is taking legal responsibility for a recorded subdivision map that permanently restructures property rights.

This is not “site plan drafting.”

This is title-level legal infrastructure.

The county specifically requires a condominium plan prepared by a licensed professional before approval.

Do You Need Separate Utility Meters?

Usually, yes.

This is another place where people confuse rental ADUs with condo-sale ADUs.

A rental ADU can often share utilities with the main house.

A separately sold condo unit? Different story.

Most lenders, buyers, and title companies want:

• Separate electric
• Separate water
• Separate gas
• Independent billing capability

SDG&E Rule 16 Requirements

SDG&E’s current rules generally require individually metered residential units in multi-occupancy developments.

Water is more flexible.

The City of San Diego still allows master meter structures in some condominium setups where the HOA manages allocation internally.

Official city water guidance:

City of San Diego Water Meter Standards

But practically speaking?

Separate meters make resale much cleaner.

They also reduce future HOA disputes. Which absolutely matters in a two-unit condo arrangement where both owners share one property.

Section 2: The Mortgage Problem Nobody Warns You About

This is where most projects die.

Not permitting. Not construction.

The lender.

Will Your Mortgage Company Allow You to Sell the ADU Separately?

Maybe.

Maybe not.

AB 1033 requires “Lienholder Consent.”

That means every lender with a recorded interest in your property must approve the condo split before recordation.

That includes:

• Primary mortgage lenders
• HELOC providers
• Second-position loans

And here’s the uncomfortable truth.

Many traditional lenders still have no internal workflow for AB 1033 conversions in 2026.

They weren’t built for this.

From the lender’s perspective, you’re changing the collateral securing their loan. That is a massive underwriting event.

The county itself acknowledges this issue directly in its draft guidance documents.

What Is a Partial Release of Mortgage?

In theory, the lender can release the ADU portion from the mortgage while keeping the main house secured.

This is called a partial release.

In practice?

Still uncommon in residential lending.

Most homeowners are ending up in one of three scenarios:

1. Full refinance
2. Collateral modification
3. Payoff and replacement financing

That’s why choosing the lender upfront matters more now than ever.

Can You Build First and Condo-Convert Later?

Yes. Many people are doing exactly that.

But there is a catch.

If you’re financing construction today, you should strongly consider whether the lender has future AB 1033 flexibility already built into the loan structure.

Because refinancing later during higher-rate environments can destroy the ROI.

And rates in 2026 are not exactly cheap.

How Does This Affect Your Existing Interest Rate?

Potentially dramatically.

Imagine this scenario:

• You refinanced in 2021 at 2.9%
• You now want to condo-convert in 2026
• Your lender refuses lienholder consent
• You must refinance into a 6%+ environment

That changes the economics overnight.

Some homeowners are discovering the increased ADU resale value still makes the math work. Others realize the refinance wipes out a major portion of the benefit.

Timing matters.

Structure matters.

Lender selection matters even more.

Section 3: The ROI Math That Changed Everything

This is the section everyone cares about.

And frankly, this is why AB 1033 is exploding in interest across San Diego.

What Is the “Condo Premium”?

Here’s the simplest way to understand it.

A traditional ADU adds value to your home.

A condoized ADU becomes its own asset.

Those are completely different valuation models.

A standard ADU might add:

• $150k
• $200k
• maybe $250k

to overall appraised value.

But a separately sellable condo unit in North Park or Clairemont might independently sell for:

• $450k
• $550k
• even higher in constrained inventory markets

Why?

Because there are thousands of buyers who cannot afford a $1.1 million detached home but absolutely can afford a smaller entry-level condo.

That buyer pool is huge.

And that’s the real financial unlock behind AB 1033.

How Fast Do You Recoup the Conversion Costs?

Usually immediately.

Seriously.

Let’s use rough math:

• Conversion soft costs: $75k
• Additional utility and legal work: $25k
• Total conversion carry: $100k

If separate sale increases exit value by $300k-$500k versus a normal ADU appraisal scenario, the conversion spread massively outweighs the conversion expense.

That’s why investors are paying attention.

The separate title creates liquidity.

Liquidity creates value.

Rent the ADU or Sell It?

This is the biggest strategic decision homeowners face.

Let’s compare.

Scenario A: Rent the ADU

Monthly rent:

• $3,500/month

Annual gross:

• $42,000

10-year gross income:

• $420,000

Sounds great.

Until you subtract:

• vacancies
• repairs
• taxes
• insurance
• management
• inflation-adjusted maintenance
• tenant risk

Now compare that to immediate sale.

Scenario B: Sell the Condoized ADU

Immediate sale:

• $550,000

Potential uses:

• pay off mortgage
• eliminate consumer debt
• fund retirement
• invest elsewhere
• buy another property

That changes household balance sheets instantly.

Some homeowners prefer long-term cash flow.

Others want debt elimination immediately.

Neither is universally correct.

But homeowners should stop pretending these are equivalent strategies. They aren’t.

One is long-term yield.

The other is immediate liquidity creation.

Section 4: Property Taxes, HOA Fees, and Long-Term Carry

This is another area filled with bad information online.

Will Selling Your ADU Trigger a Reassessment of the Main House?

Generally, no.

This is one of the most misunderstood parts of AB 1033.

Under California Prop 13 rules, the original residence typically retains its existing adjusted base-year value.

Only the newly sold condo unit gets reassessed at the new sale price.

That’s because the subdivision itself is generally treated as a segregation event rather than a full taxable reassessment of the entire property.

Official California BOE guidance:

California BOE Change in Ownership Guidance

And:

California BOE Property Assessment Rules

This is a massive advantage.

If homeowners had to fully reset their original home’s property taxes every time they condoized an ADU, almost nobody would do this.

Who Pays the Property Taxes on the ADU After Sale?

The new owner.

Which means the original homeowner permanently removes:

• future taxes
• maintenance share
• insurance share
• financial responsibility

That matters more than people realize.

Especially for retirees sitting on low Prop 13 tax bases.

What Do Small ADU HOA Fees Usually Cost?

Typically:

• $150-$300/month

These HOAs are usually tiny.

Two-unit associations are common.

The fees generally cover:

• shared roof maintenance
• driveway repairs
• common insurance
• exterior obligations
• reserve funding

The CC&Rs matter enormously here.

Poorly drafted HOA documents create lawsuits later.

This is not the place to cheap out on legal drafting.

2026 Neighborhood Spotlight: City vs County

This split matters more than most homeowners realize.

The City of San Diego Moved First

Areas like:

• North Park
• Clairemont
• Normal Heights
• University Heights

already have an established AB 1033 framework under the city’s 2025 ordinance.

The city also currently imposes stronger resale marketing rules, including owner-occupant listing disclosures.

Official city ordinance materials:

San Diego Ordinance O-21989

The County Just Joined the Market in 2026

Areas like:

• Fallbrook
• Lakeside
• Ramona
• Valley Center

only entered the AB 1033 market in April 2026.

And the county is still actively reviewing:

• owner occupancy rules
• first right of refusal rules
• investor limitations
• attached ADU restrictions

Official county draft review materials:

San Diego County Draft ADU Ordinance Options

That means the rules are still moving.

Homeowners in unincorporated areas should pay close attention to the final 2026 revisions.

The homeowners who will benefit most from AB 1033 are not necessarily the people chasing maximum rental income.

They’re the homeowners sitting on large amounts of trapped equity who want flexibility.

Some want retirement liquidity.

Some want to help adult children buy homes.

Some want to eliminate debt without leaving San Diego.

And some simply realize a separately sellable ADU is financially worth far more than a permanently attached rental structure.

That realization is why AB 1033 matters so much in 2026.