What Does It Cost to Defend a Residency Audit?

Search for what a residency audit costs and you will find plenty of numbers about the tax. Revenue departments report collections. Practitioners cite assessments. Newspapers write about the eight-figure cases. What almost nobody quantifies is the other side of the ledger: the professional fees you pay to argue back, whether you win or lose.

That gap matters because the two bills are separate and behave differently. The tax assessment depends on the facts of your move. The defense bill depends on something much more boring, which is how many hours a professional has to spend assembling a record you did not already have.

We went looking for a real answer across published fee schedules, audit statistics, and our own residency research for all 56 US jurisdictions. Here is what is actually documented, what is not, and why the difference is worth understanding before you need it.

New York is the most documented residency-audit program in the country, and its numbers are the ones most often quoted. PKF O’Connor Davies reports that over a recent five-year span New York initiated over 3,000 residency audits on high net worth and high income individuals each year, generated over $1 billion of revenue from them, and collected on average over $140,000 per taxpayer audited. The firm also notes that New York wins more than half its audits.

That $140,000 figure gets repeated as though it were the cost of a residency audit. It is not. It is the average tax the state collected from the people it audited. It tells you nothing about what those people paid their attorneys and accountants to get to that outcome, and nothing at all about what the roughly half who prevailed spent to prevail.

The volume is worth sitting with separately. Hodgson Russ, one of the firms that defends these cases, states that its attorneys have defended taxpayers in more than 10,000 residency audits. This is a routine, staffed practice area, not a rare event that happens to unlucky billionaires. Anyone moving from New York to Florida with meaningful income is moving inside a well-worn enforcement pipeline.

Since no state publishes a defense cost, the closest thing to an answer is what tax controversy attorneys publish about their own fees.

TaxCure puts tax attorney hourly rates on average at $200 to $550 per hour, and gives a flat-fee benchmark for audit work specifically: $2,000 to $3,500 for a straightforward audit, and $5,000 or more for a more complex one. Brotman Law, a California firm, publishes a schedule for its own market: $300 to $700 per hour for an experienced California tax attorney with an LL.M. in taxation, a $2,500 to $10,000 flat fee to protest a 30-day letter, and an initial retainer of $10,000 to $25,000 for multi-year field exams, replenished as needed. The same schedule puts a contested federal Tax Court case at $25,000 to $100,000 or more.

Read those ranges against what a residency audit actually is and the picture sharpens. A residency audit is never the straightforward end of the scale. It is multi-year by construction, since the state has to test whether a claimed move was genuine and sustained rather than a one-year paper exercise. It is fact-intensive rather than legal, so the work is document handling rather than brief writing. And it frequently runs through more than one stage, since an examination result you disagree with has to be protested and can be appealed further.

When we built residency dossiers for all 50 states, Washington DC, and the 5 US territories, defense cost was one of the fields we tried to fill for every jurisdiction. For most of them we came back empty, and the emptiness is the finding.

California produced the only usable range. There are no official published figures, but tax attorneys and CPAs who handle contested California residency cases informally put defending one through the administrative process at roughly $15,000 to $75,000 or more, with costs climbing sharply if the dispute proceeds to the Office of Tax Appeals. For anyone moving from California to Texas ahead of an equity event or a company sale, that is the range worth budgeting against, and it sits on top of whatever tax is ultimately owed.

New York produced no published statewide figures at all. Practitioners describe residency audits, given how document-intensive and long-running they are, as running well into five figures in professional fees for a contested case, but firms decline to publish specific ranges. Connecticut produced nothing: no published figures specific to Connecticut residency or domicile audit defense, and no standard practitioner range.

The absence is consistent across the map, and it points at the real structure of the cost. Defense is not a product with a price. It is an hourly function of how much of your own life a professional has to reconstruct on your behalf.

Two things make a residency audit expensive, and neither is the legal question.

The first is duration. Brotman Law describes a California residency audit as typically taking 6 to 24 months, with complex multi-year audits running longer and appeals adding further time on top. In New York, JLD Tax notes that residency audits often begin two to three years after your claimed move, so the clock on assembling evidence starts long before the audit letter arrives. PKF O’Connor Davies is blunter still: these audits "can drag on for five years or more."

The second is the sheer breadth of what gets requested. PKF lists cell phone tracking records, EZ Pass records, credit card statements, flight occupancy records, swipe card data, medical records, social media activity, documentation of personal possessions including artwork, jewelry, and heirlooms, and school enrollment records for minor children. JLD Tax adds appointment and work calendars, travel receipts and airline records, lease or mortgage documents for every property, utility bills, voter registration, driver licenses, vehicle registrations, professional licenses, and club memberships.

Every line on that list is either something you already have organized or something a professional bills hourly to chase down, request, reconcile, and present. That is the whole cost model. The state is not charging you for the argument. Your advisor is charging you for the archaeology.

Connecticut supplies the case that shows how far the tail can run. In Daniels v. Commissioner of Revenue Services, the decedent kept homes in three states and split the year roughly five and a half months in Connecticut, three and a half months in Florida, and three months in Arizona, holding a Florida domicile declaration from 2006 along with a Florida driver license and voter registration.

He died in 2015. The Connecticut Supreme Court did not decide the domicile question until June 16, 2026, holding that an estate challenging a DRS domicile determination need only meet the preponderance of the evidence standard rather than the higher clear and convincing standard the trial court had applied, and remanding for a new trial. That is eleven years from death to a ruling that sends the case back to start the fact-finding over.

The lesson for anyone moving from Connecticut to Florida is not that this outcome is typical. It is that domicile exposure does not end when the tax years close or even when the taxpayer dies, and that a fee meter attached to a fact-intensive question can run for a very long time.

One structural detail changes the cost calculation more than any fee schedule does.

In California, the Franchise Tax Board generally has four years from the filing date to assess on a filed return. If no return was ever filed for a year the FTB believes you owed tax as a resident, there is no statute of limitations at all under R&TC section 19057(a). New York works the same way at the edges: generally three years from filing, extending to six if more than 25% of income was omitted, and no time limit whatsoever if no return was filed, if federal changes were never reported, or if the return was false or fraudulent. Connecticut allows DRS three years for a deficiency assessment under Conn. Gen. Stat. section 12-733, with no time limit for fraudulent or unfiled returns, and since Public Act 22-117 a ten-year window to collect an assessed liability.

The group carrying the largest open-ended cost exposure, then, is not the careful part-year filer. It is the person who quietly filed nothing in the state they left and assumed the years would age out. They will not.

Nothing in the fee schedules is negotiable in a way that helps much. Hourly rates are what they are. What is controllable is the number of hours, and the number of hours is set almost entirely by whether the record already exists.

A contemporaneous record of days and nights in each state, residence and utility evidence for the new home, and documentation of retained ties to the old state costs a professional a fraction of what it costs them to reconstruct the same picture from subpoenaed toll data, cleared location history, and four-year-old card statements. That is the difference between an engagement that reviews a file and an engagement that builds one under deadline.

If you want to see where your own days have actually fallen, the Google Timeline residency importer reads your existing location history entirely in your browser, checks it against each state’s real threshold, and uploads nothing anywhere. Inside ResidencyIQ, the Mobility Map tracks days and nights across states as they happen, Evidence Vault organizes the residence, financial, and travel documentation behind a presence claim, AuditIQ flags gaps and retained-tie exposure, and advisor sharing lets a CPA or tax attorney review the record directly rather than assembling it from scratch.

This article is informational and does not evaluate any individual’s tax situation. ResidencyIQ is not a law firm or accounting firm; work with a qualified CPA or tax attorney on your own residency change.

PKF O’Connor Davies, "Moving from a High Tax State? Be Prepared for a Residency Audit," is the source of the New York figures on audit volume, total revenue, average collection per taxpayer, the state’s win rate, the five-year-plus duration, and the evidence categories auditors request: https://www.pkfod.com/insights/moving-from-a-high-tax-state-be-prepared-for-a-residency-audit/.

Hodgson Russ LLP, "Tax Residency Attorneys," states the firm has defended taxpayers in more than 10,000 residency audits: https://www.hodgsonruss.com/what-to-expect-in-a-new-york-residency-audit.html.

TaxCure, "Tax Attorney Costs and Considerations," provides the national hourly range and the flat-fee benchmarks for straightforward and complex audits: https://taxcure.com/tax-professional/tax-attorney/attorney-cost.

Brotman Law, "How Much Does a Tax Attorney Cost in California?," publishes the California hourly range, the 30-day letter protest flat fee, the multi-year field exam retainer, and the contested Tax Court range: https://sambrotman.com/tax-attorney-cost-california/.

Brotman Law, "Surviving a California Residency Audit," is the source of the 6 to 24 month typical FTB residency audit timeline: https://sambrotman.com/the-ultimate-guide-to-personal-income-tax-residency-in-california/how-to-survive-a-california-residency-audit/.

JLD Tax, "NY Residency Audits," describes the two to three year lag before a New York residency audit opens and lists the records auditors request: https://jldtax.com/ny-residency-audits/.

Shipman & Goodwin LLP’s analysis of Daniels v. Commissioner of Revenue Services, SC 21150 (June 16, 2026), covers the preponderance of the evidence holding and the decedent’s three-state split: https://www.shipmangoodwin.com/insights/historic-connecticut-supreme-court-decision-softens-the-burden-of-proof-in-estate-tax-domicile-disputesbut-significant-questions-remain.html. The decision itself: https://law.justia.com/cases/connecticut/supreme-court/2026/sc21150.html.

Klasing Associates, "The Statute of Limitations for California Tax Audits," covers the four-year assessment window and the unlimited window for unfiled returns under R&TC section 19057(a): https://klasing-associates.com/statute-of-limitations-for-california-tax-audits/.

Connecticut General Statutes section 12-733, Limits on time for deficiency assessments: https://law.justia.com/codes/connecticut/title-12/chapter-229/section-12-733/.

The California and New York defense cost ranges, and the finding that Connecticut publishes none, come from ResidencyIQ’s own dossier research for all 56 jurisdictions, summarized in the California and New York residency guides with their underlying citations.