Credit & Debt Management

FICO mechanics, mortgages, and the math of refinancing.

Understand what actually moves a US credit score, how mortgage underwriting reads your file, and when refinancing tends to make sense.

300–850 Standard FICO score range

35% Weight of payment history

Scoring

The five factors inside a FICO score

Payment history — the heaviest factor

On-time payments across credit cards, loans, and other accounts make up the largest share of a typical FICO score. A single missed payment reported to the bureaus can affect a score more than most other single actions.

Credit utilization

The ratio of reported balances to credit limits is the second-largest factor. Keeping reported utilization low, both per card and overall, is one of the more actionable levers a consumer controls month to month.

Length of credit history

The age of your oldest account and the average age across all accounts both factor in — which is part of why closing your oldest card can sometimes work against a score.

Credit mix & new credit

A mix of installment loans and revolving credit, alongside a measured pace of new applications, rounds out the remaining factors. Opening many accounts in a short window can temporarily lower a score.

Home Financing

Mortgages: What underwriters actually check

Debt-to-income ratio

Lenders compare your total monthly debt payments to gross monthly income. Most conventional loan programs look for this ratio to sit under commonly cited thresholds, though exact limits vary by lender and program.

Down payment & PMI

Putting down less than 20% on a conventional loan typically triggers private mortgage insurance (PMI), an added monthly cost that continues until sufficient equity is reached.

Rate locks

A rate lock holds an agreed interest rate for a defined window while a loan closes, protecting a buyer from rate movement during underwriting — usually for a fee or a slightly adjusted rate.

Refinancing

When refinancing tends to make sense

The break-even calculation

Refinancing usually carries closing costs. A common way to evaluate the decision is dividing those costs by the monthly payment savings to estimate the break-even point in months, then weighing that against how long you plan to stay in the home.

Rate-and-term vs. cash-out

A rate-and-term refinance adjusts the interest rate or loan length without changing the balance meaningfully, while a cash-out refinance increases the loan balance to access home equity as cash.