MORTGAGE CALCULATOR

Principal & Interest (P&I)

Principal and interest form the foundation of your mortgage payment. Principal is the portion of your payment that reduces the amount you borrowed, while interest is the cost of borrowing from your lender.

Your principal and interest payment is determined by your purchase price, down payment, loan term, and interest rate. For buyers using a mortgage calculator in San Diego, this is typically the starting point — but it is only one part of the overall payment picture.

If you choose a fixed-rate loan, this portion of your monthly mortgage payment remains stable for the life of the loan, offering predictability as you plan for long-term ownership.

Property Taxes in San Diego

San Diego property taxes are one of the most important ongoing costs to account for when estimating your monthly payment. In California, property taxes are generally based on approximately 1% of the home's assessed value, plus voter-approved bonds, local assessments, and any applicable special taxes.

In San Diego County, the effective tax rate often falls between 1.1% and 1.3%, depending on the city, neighborhood, and whether the property carries additional obligations like Mello-Roos in San Diego.

Our calculator defaults to 1.14%, but tax rates can vary significantly by community. If you are comparing neighborhoods like Pacific Highlands Ranch, Rancho Santa Fe, or Del Sur, it is important to understand how those differences affect your monthly payment.

What Is Proposition 13?

Proposition 13 is one of the most important laws shaping California property taxes. Passed in 1978, it limits the base property tax rate to 1% of assessed value and caps annual increases in that assessed value at no more than 2% per year.

For home buyers, this means your property taxes are based on the price you pay when you buy — not what the seller may have been paying. This is why two nearly identical homes can have dramatically different tax bills.

For anyone calculating the true cost of homeownership in San Diego, understanding Proposition 13 is essential because it directly affects your long-term financial picture.

What Are Supplemental Property Taxes?

One of the most overlooked costs when buying a home in San Diego is the supplemental property tax bill.

When a property changes ownership, the county reassesses it at the new purchase price. If that value is higher than the seller's assessed value, the county issues a separate one-time bill for the difference covering the remainder of the tax year.

This bill is often not included in your lender's initial escrow estimate, which can catch buyers off guard. Depending on when you close escrow, you may receive one or even two supplemental bills.

This is an important cost to plan for when estimating your total cash needed to close.

Assessed Value vs. Market Value

These two terms are often confused, but they serve very different purposes.

Market value is what a buyer is willing to pay for a home based on current market conditions, comparable sales, location, and demand. This is what determines your purchase price.

Assessed value is what the county uses to calculate your property taxes.

In California, Proposition 13 allows your assessed value to rise slowly over time, even when market values increase much faster. This creates one of the long-term financial benefits of homeownership in California and is an important distinction when evaluating the cost of owning a home in San Diego.

Homeowners Insurance

Most lenders require homeowners insurance in San Diego, and in most cases, your lender will collect it as part of your monthly mortgage payment through escrow.

Insurance costs vary based on the home's value, replacement cost, age, and location. Homes located in higher wildfire-risk areas may carry significantly higher premiums, especially as California homeowners insurance rates continue to rise.

For many buyers, homeowners insurance costs in San Diego often range between $100 and $250 per month, though that number can vary widely depending on the property and coverage.

Because insurance directly affects your monthly payment, our lender partners can help provide more accurate estimates based on the neighborhoods you are considering.

HOA Dues

Many homes in San Diego — especially in master-planned communities like Pacific Highlands Ranch, Carmel Valley, Del Sur, San Elijo Hills, and Rancho Tesoro — include monthly HOA dues.

HOA fees can cover shared amenities, community landscaping, pools, clubhouses, gated security, and neighborhood maintenance. While HOA dues add to your monthly housing costs, they often contribute to community upkeep and long-term property value stability.

When using a mortgage calculator for San Diego homes, HOA dues should always be factored into your affordability analysis.

What Is Mello-Roos?

Mello-Roos in San Diego is a special tax assessment commonly found in newer master-planned communities. It helps fund infrastructure such as schools, parks, roads, and utilities.

Unlike standard property taxes, Mello-Roos is billed separately and can add hundreds or even thousands of dollars annually to your cost of ownership.

Many North County San Diego communities carry Mello-Roos, including Pacific Highlands Ranch, Santaluz, 4S Ranch/Del Sur, Bressi Ranch, San Elijo Hills, and Poway. Understanding whether a property has Mello-Roos — and how much — is critical when estimating your monthly payment and determining true affordability.

You can learn more in our guide: What Is Mello-Roos in San Diego? →