Leftover pay is not a cost-of-living index

Most relocation articles start with a percentage. San Francisco is 70% above the national average. Houston is 8% below. The implied next step is arithmetic: take your current spending, multiply by 1.70, and you know what life costs on the Bay.

That arithmetic is wrong for a household that is actually moving. An index prices a basket — a studio or a two-bedroom mixed into a metro-wide average, a transit pass you may not buy, restaurant meals you may not eat, and no income tax at all. It is a comparison of price levels, not a comparison of what you keep.

Uprootmap starts from the other end. Take the salary your job pays in that metro (or the remote salary you keep), apply federal, state and city wage tax, subtract rent at your bedroom count, then subtract groceries, utilities, healthcare, getting around and childcare for the people in the house. What remains is leftover. That is the number on every city page, every ranking, and every head-to-head.

A typical published index (ACCRA / C2ER, some news calculators, a lot of HR “cola” tables) blends categories with fixed weights: housing, food, transport, healthcare, utilities, miscellaneous. Housing is usually a metro-wide average rent or a blended owner-equivalent. Food includes groceries and restaurants. Transport assumes a car in most metros and a transit mix in a few.

Three things fall out of that design:

• Your tax bill is invisible. Moving from Chicago to Austin drops Illinois's flat income tax and adds no Texas wage tax — but Austin's property tax is among the steepest in the country. An index that only watches prices will rank those two cities by rent and groceries and miss the largest legal difference between them.
• Your household is average. A couple that needs three bedrooms is not buying the same housing as a single person in a one-bedroom. The gap between those units is not a constant across metros. New York's studio-to-three-bed spread looks nothing like Austin's.
• Your job's local pay is someone else's. Nurses, teachers and software developers do not get the same raise (or cut) when they change metros. An index that holds income constant is answering a remote-worker question, even when the reader is not remote.

None of that makes indexes useless. They are a decent way to say “groceries are expensive here.” They are a bad way to decide whether you can afford the move.

Leftover on this site is one equation, run the same way for every metro:

• Gross pay — local market pay for your occupation, or your remote salary held flat.
• Minus federal income tax, Social Security, Medicare, state income tax, and city wage tax where it exists (Philadelphia, New York City, Baltimore, and a handful of others).
• Minus asking rent at the bedroom count you set.
• Minus a household-sized bundle of groceries, healthcare, utilities, transport and childcare, scaled by that metro's non-housing price level.

Debt payments, tuition, travel and your savings rate are deliberately left out. Those are yours, not the city's. The methodology writes down every rate, every baseline and every source.

The result is a dollar figure you can compare. “Austin leaves about $1,200 more a month than San Jose for this household” is a sentence you can take to a spreadsheet. “Austin is 12% cheaper” is not, until you know 12% of what, after which tax.

Take the site's default profile: a registered nurse living alone, renting a one-bedroom, currently in Chicago. Open Austin, San Francisco and Houston and you will see three leftover numbers, not three percentages.

Texas has no state income tax. California does, and San Francisco's asking rent is in a different league from Houston's. A COL index will tell you San Francisco is “much more expensive” and Houston is “a bit cheaper than Chicago.” Leftover will also show the Illinois tax you stop paying, the local wage you would earn as a nurse in each market, and the fact that a one-bedroom — not a metro-wide average — is what this person is actually renting.

Switch the same profile to two adults and three bedrooms and the ranking moves. Houston and Dallas often look better for larger units than coastal metros whose apartment stock is studio-heavy. That is the bedroom-count problem again: the index blended it away.

Switch pay to remote and hold the Chicago salary constant. Leftover in Tulsa, Omaha or Knoxville jumps, because you kept a high-cost-metro paycheck and dropped the high-cost rent. An index that already assumed a national salary will understate that move; one that assumed a local salary will overstate it. The checklist guide walks through which switch to flip first.

Nine states plus a few more charge no wage income tax. That is a real raise — on paper. The same states often collect it back in property tax (Texas), sales tax (Tennessee), or both. Washington has no income tax and some of the highest home prices on the West Coast. Florida has no income tax and a homeowners-insurance market that does not appear in a grocery index.

City wage taxes are worse, because a lot of calculators skip them. Philadelphia's 3.75% city wage tax and New York City's local income tax are the reason those metros look worse here than on sites that stop at the state line. If you are comparing Philadelphia vs Pittsburgh, that local tax is the plot, not a footnote.

The state tax and rent tradeoffs guide is the longer version of this, with pairs worth opening.

Use a COL index when you want a feel for grocery and restaurant prices, or when you are writing a cost-of-living adjustment for a workforce that will stay in place. Use leftover when a specific household is deciding whether to move.

Also use leftover when the question is “which four metros are worth a weekend of listing research?” That is what the rankings and the city directory are for. The model is wrong in the third digit by construction. It is good enough to throw out the forty cities that do not work for this paycheck.

1. Set the household on the homepage — job, salary or local-market pay, adults, kids, bedrooms, remote vs local.
2. Open the full metro ranking. Ignore the order below the top handful until you have changed one input and watched it move.
3. Open two or three city pages and read leftover against the tax line and the rent line, not against a percentage.
4. If two cities are close, use a head-to-head such as Chicago vs Austin so both tax codes run on the same household.

Then go look at real listings. Leftover is a filter, not a lease. How much leftover do you need before you move is the recoup test once you have a dollar gap. Two searches this site already answers with leftover, not an index: Is Reno cheaper than Las Vegas?, Las Vegas to Reno leftover, Is Texas cheaper than California after tax? and San Francisco to Austin.