Key takeaways
- Most conforming loans run through automated underwriting first; humans verify the file matches.
- Underwriters evaluate capacity, credit, capital, and collateral.
- Conditional approval is normal — the conditions are the actual work.
- New debt, job changes, and unsourced deposits kill deals after approval.
Automated first, human second
Conforming loans are submitted to an automated underwriting system — Fannie Mae's Desktop Underwriter or Freddie Mac's Loan Product Advisor — which returns a recommendation and a list of documentation requirements. A human underwriter then verifies the file supports what was entered.
Manual underwriting applies when the automated system will not approve, or for products outside agency guidelines. It is more forgiving of unusual circumstances and less forgiving of weak ratios, because a person is making a judgment rather than a model returning a score.
The four Cs
Capacity is your ability to repay, measured through debt-to-income and income stability. Credit is your history of repayment. Capital is your assets, down payment, and reserves after closing. Collateral is the property itself, established by the appraisal.
Weakness in one area can be offset by strength in another, which is what underwriters mean by compensating factors. Large reserves offset a higher DTI. A long employment history offsets recent credit blemishes. This is why two borrowers with identical scores get different outcomes.
Conditions and what kills deals late
Conditional approval means the underwriter will approve once specific items are provided: a letter of explanation for an inquiry, sourcing for a deposit, an updated pay stub, evidence a collection was paid, proof a business is active. Turn these around same-day — files sitting in condition status are the main cause of delayed closings.
Late-stage failures follow a pattern: opening new credit, financing furniture or a car before closing, changing jobs or pay structure, and large deposits without a documented source. Lenders re-pull credit and re-verify employment days before closing. Change nothing until you have keys.
Frequently asked questions
How long does underwriting take?
Initial underwriting typically runs one to five business days depending on lender volume. The full contract-to-close timeline is usually 30 to 45 days, most of which is spent clearing conditions and waiting on the appraisal.
What is a letter of explanation?
A short written statement explaining an item in your file — a credit inquiry, an address gap, an employment change, a large deposit. Be factual and brief; underwriters are documenting the file, not judging you.
Can I switch lenders mid-process?
Yes, but you restart the timeline and repay some third-party costs. Do it only if the savings are substantial or the current lender is failing to perform.
Sources & further reading
- Fannie Mae Selling Guide, Part B — Origination Through Closing
- Freddie Mac Seller/Servicer Guide
- Consumer Financial Protection Bureau, What is underwriting
Figures and rules change. Verify current requirements with the issuing agency or a licensed professional before acting.