Underwriting Your Own Income

Size the loan against the income that survives a bad year, insure the income you cannot replace, and hold the reserves outside the house. Those three moves cost almost nothing and eliminate most of the ways a mortgage actually destroys a household. Everything else in this subsection is detail.

Start from what the instrument really is. A mortgage is a fixed nominal liability — a contractual stream of certain payments, indifferent to your circumstances. It is funded by your human capital, which is a risky, illiquid, undiversifiable asset that pays nothing when it is impaired and cannot be sold, hedged, or borrowed against. Pairing a certain liability with an uncertain asset is the mismatch, and no amount of home appreciation fixes it. The lender understood this from the beginning — recall that a mortgage is underwritten as a bet on your future income, with the house merely as collateral (section “True Affordability in the Housing Market”). You should underwrite the same bet, on stricter terms, because the lender’s downside is the house and yours is everything.

Measure the runway, not the payment. The number that decides whether an income shock becomes a foreclosure is months of survivable time:

Set the target from how long your income actually takes to replace, and be honest that the relationship runs the wrong way from intuition: the more specialized and highly compensated the role, the thinner the market for it and the longer the search. A generalist mid-career professional may re-employ in three months; a senior executive in a narrow field, a partner-track specialist, or anyone whose compensation depends on a particular firm’s equity should plan on nine to eighteen. Then add the recognition that the searches lengthen precisely in the downturns that cause them. Twelve months of $R$ is a floor for a single-income household with specialized skills, not a conservative luxury. The sizing framework is in section “Sizing the Fund”; what this chapter adds is that the mortgage payment belongs in the denominator at its full amount, forever, because it is the one outflow that never compresses.

The mitigations, ranked by leverage per dollar spent.

Underwrite on income you would still have

Qualify with the lender on everything; commit based on base salary alone. Bonus, commission, RSUs, and a second earner’s income are all real — and all first to disappear in the scenario you are protecting against. Take the housing ratio of section “Housing Ratio (HR1)”, apply it to base pay net of tax (section “The Gross-DTI Trap for High Earners in High-Tax States”), and treat the result as the ceiling. A household earning $700,000 of which $300,000 is base has a very different survivable payment than the lender’s model believes. This is the only mitigation that is free, permanent, and cannot lapse.

Own-occupation disability insurance

During your working years, disability is substantially more likely than death, and it is the shock that removes the income while leaving every expense in place — including, cruelly, new medical ones. Group long-term disability through an employer typically replaces 60% of base pay, is capped at a monthly maximum that a high earner blows through immediately, is taxable when the employer paid the premium, and terminates when the job does. Buy an individual own-occupation policy with a true own-occupation definition and residual benefits, paid with after-tax dollars so the benefit arrives tax-free (section “The Contract Terms That Actually Matter at High Incomes”).

Term life sized to the liability

If a survivor could not carry the mortgage on their own income, the gap is an insurable risk with a cheap solution: level term to the year the balance becomes survivable, laddered so coverage steps down as the loan amortizes (section “Estimating Life Insurance Needs”). Buy plain term from a third-party insurer. Do not buy the “mortgage protection” or credit-life product the lender offers at closing — the benefit declines with the balance while the premium does not, and the lender, not your family, is the beneficiary (section “Credit Life Insurance”).

Hold liquidity, not equity

Home equity is the worst possible place to store your safety margin: it earns the property’s return, cannot be spent, and is accessible only by borrowing from a lender who will decline you once you are unemployed. If a HELOC is part of your plan, open it while you are still employed — underwriting happens at origination, and an undrawn line costs little to maintain (section “Home Equity Line of Credit”). Then treat it as a backstop rather than a reserve, because lenders froze and reduced home-equity lines en masse in 2008 and 2009, exactly when borrowers reached for them. A line you cannot draw is not liquidity. This is also the argument against sprinting to prepay the mortgage while cash reserves are thin (section “The Down Payment Versus the Retirement Account”): every prepaid dollar converts a liquid asset into an illiquid one and buys you nothing on the month you lose your job, since the payment is unchanged unless you also recast (section “Recasting: The Refinance Nobody Offers You”).

Break the correlations you can see

If you work in the dominant industry of the metro you are buying in, you have stacked three positions on one bet: salary, employer equity, and now housing. You cannot diversify the house or the job, so diversify the third leg — build the liquid portfolio to underweight your own sector by roughly the value of your at-risk grants (section “Human Capital and Asset Allocation Across the Life Cycle”). And check the correlation inside your own household: two incomes at the same employer, or in the same industry, is one income for underwriting purposes.

Prefer the fixed rate when income is volatile

An adjustable rate adds a second random variable to a balance sheet that already has one. The point is not that rates will necessarily rise; it is that a volatile income deserves a liability with no uncertainty in it at all, so that when something goes wrong you are managing one problem instead of two.

And keep the exit cheap. The mitigations above reduce the probability of a forced sale. None of them changes the fact that selling a house takes months and costs 8–10% (section “True Affordability in the Housing Market”). If your income is genuinely fragile — early-stage equity, a single concentrated client, a visa tied to one employer — the correct hedge may not be an insurance product at all. It is renting for another two years, which converts a levered, illiquid, correlated position into a thirty-day notice period. That option has real value, and it is the one the spreadsheet never prices.