Look, the absolute worst time to discover your mortgage preapproval was built on quicksand?
Right after the seller says "yes" to your offer.
Now you've got earnest money locked up. You already paid for the inspection. The appraisal's probably ordered. Your closing date's circled on the calendar in red Sharpie.
Maybe you've already told your landlord you're out. Your boxes are half-packed. The moving truck's scheduled.
Then your lender calls.
"Uhh... we found a problem."
THAT is what I'm talking about when I say "fake preapproval letter."
I'm not saying someone literally forged a document. I'm saying someone handed you a preapproval letter before doing enough actual work to know if the loan behind that letter even made sense.
Big difference.
After more than 20 years in this business, I'd rather discover an ugly problem BEFORE you fall in love with a house than AFTER you're under contract with your life plans already in motion.
This post breaks down what a REAL preapproval actually requires. By the end, you'll know:
- Why the assumptions behind the letter matter way more than the number printed on it
- The difference between "preapproved" and actually fully approved
- Where income calculations go sideways (and why your paystub isn't the whole story)
- How one missed debt can blow up your entire file
- Why the actual house changes everything about your preapproval
- What happens when a preapproval falls apart after you're under contract
- The exact questions you need to ask your lender before you write an offer
Let's dig in.
1. A Preapproval Letter Is Only as Good as the Numbers Behind It
A piece of paper saying you're approved for $600,000 doesn't magically make you a $600,000 buyer.
The assumptions behind that letter are what actually matter:
- What income did the lender use?
- What debts did they count?
- What money did they verify for your down payment and closing costs?
- What loan program did they plug in?
- What interest rate did they assume?
- How much did they estimate for property taxes?
- What did they use for homeowners insurance?
- Did they include HOA dues?
- What type of property are you planning to buy?
Change one or two of those numbers? Your $600,000 preapproval starts looking different.
Change several of them? The entire approval might vanish into thin air.
This is why I don't start with, "Hey, how much house do you qualify for?"
I want to know how the numbers were actually built.
2. "Preapproved" Doesn't Mean the Loan Has Been Fully Approved
There's an important distinction buyers need to understand.
A lender can issue a preapproval before every piece of your loan has been verified and reviewed by an actual underwriter. The Consumer Financial Protection Bureau even points out that getting a Loan Estimate doesn't mean the lender has approved OR denied your mortgage. More financial information still has to be reviewed as the loan moves forward.
For conventional loans, Fannie Mae requires lenders to verify and document the financial information being used to qualify you. That includes income, employment, assets, liabilities, credit information, and other factors affecting your ability to repay the mortgage.
So getting an automated underwriting approval? Important.
But the information entered into that system still needs to be accurate.
Here's the deal: Garbage numbers going into an underwriting system produce a pretty useless approval coming back out.
3. Income Is One of the Biggest Places Preapprovals Go Sideways
Let's say you make $100,000 per year.
Someone glances at your salary and enters $8,333 per month.
Easy, right?
Except your income might not be that simple.
Maybe you get overtime. Maybe you earn commissions. Maybe you have bonuses. Maybe you work variable hours. Maybe you juggle two jobs. Maybe you own a business. Maybe you recently changed jobs.
Mortgage underwriting has rules for determining what income actually gets used to qualify. Fannie Mae's current guidance says qualifying income needs appropriate documentation and generally needs to show stability, history, and a reasonable expectation of continuing.
Translation: The number on your paystub and the number underwriting uses aren't always identical.
Suppose the original preapproval used $8,333 per month. After documentation gets reviewed, underwriting determines the qualifying income is actually $7,300.
Your income didn't suddenly change.
The mortgage calculation changed.
And now your debt-to-income ratio changes right along with it.
4. The Debt Side Matters Just as Much
I have the same concern with debts.
Someone pulls your credit report. They see your car payment and credit cards.
Done, right?
Not even close.
Mortgage underwriting looks way beyond a quick glance at the credit report.
Fannie Mae requires lenders to consider liabilities affecting your ability to make the mortgage payment. Those obligations include revolving accounts, installment loans, leases, real estate loans, HELOCs, child support, and other recurring debts. Current guidance also covers specific treatment for student loans, tax installment agreements, business debt, and other obligations.
A debt missed during preapproval can change your entire file.
Suppose someone forgot about a $600 monthly obligation. That's $7,200 per year of additional debt underwriting suddenly has to consider.
Now run your debt-to-income ratio again.
The answer might be very different.
5. The Actual House Changes the Preapproval Too
This surprises buyers.
We don't just approve YOU. Eventually, we also have to finance a specific property.
That matters here in Middle Tennessee because two homes selling for exactly the same price can produce totally different monthly payments.
A $600,000 house in Franklin might have one tax bill. A $600,000 house somewhere else might have another. One neighborhood might have no HOA. Another might slap you with $150 monthly. Homeowners insurance varies all over the place. Flood insurance enters the equation on certain properties.
Then you get into property types:
- Condo
- Townhome
- Four-unit property
- House with an ADU
- Large acreage
- Unusual construction
- Investment property
- Second home
Each situation creates different questions.
So when I talk with buyers, I prefer using numbers from homes they're realistically considering instead of plugging some generic property tax and insurance estimate into a calculator and calling it a day.
6. Your Mortgage Payment Matters More Than the Number on the Letter
This is another mistake I want buyers to avoid.
You might qualify for the payment.
That doesn't mean you should WANT the payment.
Those are completely separate conversations.
I've worked with buyers whose underwriting numbers allowed them to spend more than they wanted to spend. I've also worked with borrowers who had higher debt-to-income ratios where the complete financial situation made way more sense than the ratio alone suggested.
The goal should NOT be getting the biggest preapproval letter possible.
The goal should be figuring out a payment range where you actually feel comfortable, then determining what purchase price fits that range.
That conversation should include real estimates for taxes, insurance, HOA dues, and the loan structure.
Write this down: Figure out the payment first. THEN you shop for houses. Not the other way around.
7. What Happens When the Preapproval Falls Apart After You're Under Contract?
This is where the mortgage problem turns into a full-blown real estate crisis.
Underwriting identifies an issue. Now everybody starts scrambling for a solution.
Maybe the income needs to be recalculated. Maybe a debt needs to be paid off. Maybe you need additional cash. Maybe the loan program needs to change. Maybe the purchase price needs to change. Maybe there's another legitimate source of income or an underwriting guideline nobody considered earlier.
Sometimes there's a solution.
Sometimes there isn't.
Meanwhile, your purchase contract is still moving forward. Inspection deadlines still exist. The appraisal might already be done. The seller still expects the transaction to close. Your moving plans haven't magically disappeared.
This is exactly why I hate solving preventable mortgage problems after you're already under contract.
The stakes are way higher.
8. What I Want Reviewed Before You Start Shopping
I want to know what we're dealing with BEFORE you start making offers.
That means looking beyond your credit score and annual salary:
- How you actually earn your income
- Which income underwriting will actually use
- Your debts calculated correctly
- Where your down payment and closing money are coming from
- Whether reserves matter
- What type of property you plan to buy
- The loan run through the appropriate automated underwriting system with accurate information
Then I want to talk about payment.
If you tell me you're shopping in Franklin, Spring Hill, Columbia, Murfreesboro, Nashville, or another Middle Tennessee market, I'd rather look at actual examples of homes in those areas and use realistic taxes, insurance, and HOA numbers.
That gives us a much better conversation than me saying, "Congratulations. You qualify for $600,000" and calling it a day.
9. How Do You Know If Your Preapproval Is Actually Solid?
Before you start writing offers, ask your lender a few simple questions:
- Did you actually review my income documents?
- Did you run automated underwriting?
- Did you review my debts instead of just relying on the credit report?
- Did you verify the money I need for closing?
- What property taxes and insurance did you use when calculating my payment?
- Did you include HOA dues if I'm shopping in an HOA community?
- Does anything about my income, employment, assets, credit, or property type still need additional review?
- What assumptions would cause this approval to change?
Those questions tell you way more than the fancy logo at the top of the preapproval letter.
You Want the Problems Early
Nobody likes hearing there's an issue with their mortgage application.
I get it.
But timing matters.
If I tell you BEFORE you start shopping that we have an income issue, we've got time to work through it. If we find a debt issue, we've got time to evaluate it. If your comfortable payment puts you at a lower price than you expected, we adjust the search. If an unusual property needs a different financing strategy, we figure that out before you write the offer.
Those are mortgage problems.
They become much BIGGER problems once you've got a signed purchase contract attached to them.
So if you're planning to buy a home, don't just ask:
"How much am I preapproved for?"
Ask:
"What did you actually review before you gave me this preapproval?"
The bottom line: The number printed on the letter matters. The work behind the letter matters way more.
Sources and limitations
- Consumer Financial Protection Bureau: Get a Preapproval Letter
- Consumer Financial Protection Bureau: Review Your Loan Estimates
- Fannie Mae: General Income Information
- Fannie Mae: Bonus, Commission, Overtime, and Tip Income
- Fannie Mae: Monthly Debt Obligations
- Fannie Mae: Monthly Housing Expense for the Subject Property
- Fannie Mae: Occupancy Types
- Fannie Mae: General Property Eligibility
A preapproval is based on assumptions and is not a guaranteed loan offer. Qualification, approval, payment, pricing, income, liabilities, assets, property eligibility, and required documentation depend on the complete file, loan program, lender requirements, and subject property. This article is educational and is not a commitment to lend or a guarantee that a transaction will close.
And I'd much rather find the problem before you find the house.
