The Double Contingency Trap in Arizona Construction Loans

If you are building a custom home in Arizona, you should absolutely carry a contingency in your construction budget. That is not padding the numbers — that is smart construction finance. Price changes, site issues, and change orders are a normal part of any build. The American Institute of Architects describes a contingency as a predetermined amount or percentage in the project budget to cover unpredictable changes in the work, and notes that it is a legitimate risk management tool when properly sized and managed.

The problem is not a contingency. The problem is the double contingency.

That is when the contract between you and your builder already carries a built-in contingency — and then your lender adds another overlay contingency on top of it anyway. That second layer may sound prudent in a credit memo, but out in the real world it can quietly wreck your deal. It inflates your cash to close, makes your appraisal work harder than it should, and tightens your debt-to-income ratio based on padding rather than actual project risk.

A Contingency Is Smart. A Duplicate Contingency Creates Risk.

If you and your builder already agreed to a real contingency inside the contract, and you have documented liquidity or reserves, then a second lender overlay becomes unnecessary. It is often just duplicated conservatism that costs you real money.

Construction loans do not live in theory. They work the same as every other underwrite — based on Loan-to-Value, post-closing reserves, and Debt-to-Income. Every extra dollar added to the approval stack has consequences, even if it never shows up in practice.

Where the Deal Starts to Go Sideways

Let's put real numbers behind this. Assume a build cost of $900,000. A 10% contract contingency brings the total project budget to $990,000. If the lender then overlays another 10% contingency on top of that, the underwritten cost jumps to $1,089,000. At 80% loan-to-value, that one decision changes the structure significantly — requiring roughly $79,200 of additional cash to close for risk the original contract contingency was already meant to address.

Why the Math Gets Uglier, Not Safer

This is where a lot of lenders lose the plot. An appraisal is not a reward for a bigger spreadsheet. The CFPB describes an appraisal as an independent assessment of the property's value. Fannie Mae's Selling Guide specifies that for new or proposed construction, the appraisal must be based on plans and specifications, an existing model home, or other information sufficient to identify the quality and character of the improvements.

That means the appraisal is tied to the subject property and the market evidence supporting its value — not to the size of your budget spreadsheet. When a lender inflates the budget with an overlay contingency, the appraised value does not automatically rise to match it. The borrower ends up squeezed between a much larger cost basis and an appraisal that still has to clear based on real Arizona comps.

The DTI Assumptions That Do Not Belong in Arizona

The same problem shows up in qualification. When a lender uses a padded budget to size the loan or the payment, the borrower's housing expense rises. Then some lenders compound the problem by stacking on a generic property tax assumption that does not fit the Arizona market.

A blanket 1% of build cost may work in some states, but Arizona is not one of them. The Arizona Department of Revenue shows that primary residential property is assessed at a 10% ratio, and Maricopa County publishes actual levy and rate tables by taxing jurisdiction — not one flat statewide number. Tax rates are developed by dividing the total levy by total assessed value, which means local tax treatment is granular and jurisdiction-specific. Using a generic placeholder when better local data is available is not conservative underwriting — it is just inaccurate.

When a lender overstates cost and overstates taxes, the borrower gets penalized twice by assumptions instead of facts.

The Fix: One Proper Contingency, Properly Placed

You do not solve construction risk by pretending it does not exist. You solve it by putting a practical contingency where it belongs — in the contract between you and your builder — and by matching the backstop to the actual deal.

Best practice means keeping the contingency in the contract and budget, documenting the borrower's real reserves, underwriting taxes using Arizona-specific benchmarks tied to comparable sales, and working with a lender that understands the construction-to-permanent structure well enough to offer flexibility where it actually matters.

If your builder already added a legitimate contingency into the contract, and you have reserves to handle real surprises, the right question to ask your lender is: "What risk is still uncovered?" When the answer is vague, the overlay is probably vague too — and vague overlays are expensive.

Frequently Asked Questions

References

• American Institute of Architects — Managing the Contingency Allowance
• Consumer Financial Protection Bureau — What Are Appraisals?
• Fannie Mae Selling Guide — Requirements for Verifying Completion
• Arizona Department of Revenue — Arizona Property Taxation
• Maricopa County — Tax Levy and Rates