Before you get to the interest rate, an American mortgage comes down to four variables. Understanding which ones changes how you run the purchase: three of them depend on the buyer's behavior during the process, and that is exactly where most of the problems are born.

Pillar 1 — The property

The house gets evaluated too. The bank orders an appraisal — an independent market-value assessment — because the property is the collateral for the loan. If the appraisal comes in below the negotiated price, the bank finances against the appraised value, and the difference becomes cash out of the buyer's pocket or a renegotiation with the seller.

The type of property matters as well: a condo, a single-family home, an income property or a house that needs structural work fall into different products, with different rules.

Pillar 2 — Credit score (the most volatile)

This is the pillar that swings the most and the only one that can get worse on its own during the process. The advice from professionals in the field is blunt: until the purchase closes, don't touch your credit.

What usually knocks the score down at exactly the wrong moment:

• Opening a new credit card — each application generates a formal pull (hard inquiry) and lowers the average age of your accounts.
• Financing a car — on top of the inquiry, a new monthly payment enters your DTI. It's the classic mistake: people about to change houses tend to want to change cars around the same time.
• Running up your card balances — high utilization drags the score down even with every bill paid on time.
• Closing an old card — it cuts your total available limit and shortens your history.
• Being late on any bill, including a small one.

And the detail that catches people off guard: credit is pulled again close to the closing. An approval signed weeks earlier protects nobody from a score drop along the way.

Pillar 3 — The down payment

The down payment does three things at once: it lowers the LTV, improves the rate you're offered and determines whether there will be mortgage insurance in the payment. It isn't only about “having the money”: the bank wants to see where it came from and how long it has been in the account.

Money that appeared out of nowhere requires a gift letter, proof of an asset sale or a bank trail. A family gift is accepted in most products, as long as it is documented.

Pillar 4 — Proof of income

Here's a common confusion, cleared up on the episode: having money saved does not replace having income. A high balance helps, and a consistent average balance earns points. But what holds up the approval is the monthly flow — because it's with flow that you pay the mortgage.

Money in stocks is read with reservation precisely because it swings: today's value is no guarantee of next month's. Stable, documented income counts for more in the analysis than volatile assets.

The self-employed and business owners usually present two years of tax returns; salaried employees present pay stubs, a W-2 and employment verification. Changing jobs in the middle of the process — even to earn more — can require a full reanalysis.

The practical rule

From the day you decide to buy until the day you get the keys, the goal is to be predictable: no new accounts, no new debt, no large unexplained transfers, no avoidable job change. Furniture, appliances and cars wait for the signature. It's the stage of life in which being financially boring is worth money.

This text is informational and does not replace legal, accounting or licensed mortgage professional advice. Rules, figures and rates change; confirm the current version before any decision.

Sources and verification

• Cadê Moradia episode with Rafael Na (June 2026) — the four pillars of credit analysis and the warning about score drops during the process.
• The concepts of debt-to-income (DTI) and loan-to-value (LTV) — standard mortgage underwriting criteria in the United States.
• Factors that make up the American credit score: payment history, credit utilization, age of accounts, new inquiries and credit mix.
• Appraisal — independent assessment of the property required by the lender before closing.

Watch this part of the episode:

The 4 pillars of a mortgage and the fatal mistakes you must avoid — starting at 10:13 · CADÊ BRAZIL