Nonresident state tax: when you owe a state you do not live in

State income tax follows two independent tracks. The first is residency, which exposes worldwide income to the state you belong to. The second is source, which exposes particular income to the state it arose in, whoever you are and wherever you live. Nonresident state tax is that second track, and it survives even the cleanest possible relocation.

The consequence is that leaving a state settles less than people expect. Move from New York to Florida, keep the consulting clients, keep the apartment as a rental, keep flying in for meetings, and you have not ended the New York filing obligation. You have changed which return you file.

What gets sourced to a state

The categories are reasonably consistent across states, even where the detail is not:

• Wages and salary for services physically performed in the state
• Business income from a trade or business carried on there, including a partner’s or S corporation shareholder’s distributive share
• Rent, royalties and gain from real property located there, and generally gain on the sale of an interest in an entity holding such property
• Lottery and gambling winnings from in-state sources, in many states
• Deferred compensation and equity attributable to services previously performed there, which can reach back years after the move

What is usually not sourced to a state is portfolio income of a nonresident: interest, dividends and gains on securities generally follow the taxpayer’s residence rather than any state’s borders. That single distinction accounts for a large part of why people move.

Federal law limits states in two important places. Retirement income from a qualified plan may not be taxed by a state the recipient no longer lives in, and interstate rail, motor and air carrier crews have their own protective sourcing rules.

The allocation fraction

For employees, the arithmetic that decides everything is a working-day fraction: wages multiplied by days worked in the state, over total days worked everywhere for that employer.

The denominator does more work than people anticipate. It is working days, not calendar days — weekends, public holidays, sick leave and vacation come out before the fraction is struck. A smaller denominator makes each in-state day worth proportionately more, so removing genuine non-working days is not a rounding exercise.

New York performs this on Form IT-203-B, Schedule A. The instructions take the days employed by that employer during the period of nonresidency, subtract Saturdays and Sundays not worked, then holidays, sick leave and vacation, to arrive at total working days; days worked in New York are then set against that total.

Take an employee who leaves New York in the middle of the year and keeps the same employer. Suppose the allocation period produces 130 total working days, of which 26 were spent physically working in New York. The New York fraction is 26/130, or one fifth, and one fifth of the wages earned in the period is allocated to New York regardless of what the employer withheld. If a review of the calendar shows that four of those 26 were non-working travel days rather than workdays, both the numerator and the character of the record change — which is why the underlying day evidence, not the summary, is the thing worth keeping.

Two warnings sit around this calculation. First, several states will not accept the fraction at face value where the employee is assigned to an in-state office and worked remotely by choice: that is the convenience of the employer rule, and it moves days into the numerator that you never physically spent there. Second, the allocation day count is not the same count as a statutory residency day count, and conflating them is a common and expensive error.

Allocation days are not residency days

New York statutory residency attaches where a permanent place of abode is maintained for substantially all of the year and physical presence exceeds 183 days, counted so that any part of a day present is a full day. The allocation fraction, by contrast, counts working days and asks where the work was done.

A Sunday in Manhattan is a New York day for statutory residency and no day at all for allocation. A workday spent at home in Connecticut for a New York-assigned employer may be a New York workday for allocation and not a New York day for residency. The two counters run over the same travel history and are supposed to disagree. A single ledger of dated, evidenced days is what allows both to be derived without either being reconstructed.

New York’s permanent place of abode rule was tightened recently, which matters if you are relying on older guidance about a retained apartment.

Credits for taxes paid to other states

Your resident state taxes worldwide income, so without relief the same dollar would be taxed twice. The relief is the resident credit, and it has three characteristics worth knowing before relying on it.

It is normally capped at the home state’s own tax on the same income, so where the source state’s rate is higher, the excess is simply borne. It is normally given only for tax on income the home state agrees is sourced to the other state, which is where convenience-rule cases come apart. And it is claimed on the resident return, which means the nonresident return usually has to be prepared first.

Reciprocal agreements between neighbouring states — Pennsylvania and New Jersey, and several others in the mid-Atlantic and midwest — remove the problem entirely for wages by agreeing that only the state of residence taxes them. Where one applies, the mechanics above largely fall away for employment income.

Filing thresholds

There is no national rule. Some states require a nonresident return from the first dollar of source income, some set a dollar threshold, some tie the threshold to the standard deduction or to a proportional share of it, and a number apply a de minimis number of working days before withholding is required — which is not the same thing as a threshold for the tax itself. A federal Mobile Workforce State Income Tax Simplification bill has been introduced in successive Congresses to standardise this and has not been enacted.

Two practical points follow. Withholding does not define liability: an employer that stops withholding for a state does not thereby end your obligation to it, and one that continues does not create one. And a threshold that is not met still often leaves a filing obligation, because the state wants to see the calculation that produced the answer.

What Residay tracks

The whole of this rests on a dated, evidenced record of where each day was spent. Residay records that, holds the evidence behind each attributed day, and applies the right convention where a jurisdiction counts part-days differently from the way a traveller would.

It computes the determinative New York State and City counts, projecting the date each threshold would be crossed, and asks the permanent place of abode question separately because a dwelling’s status is a legal fact rather than a location. It also tracks state-level presence for California, Florida, Nevada, Tennessee, Texas and Washington as advisory presence evidence, so that the allocation numerator for a workday in any of them is already documented.

What the app does not do is characterise a day as a working day or a non-working one, or decide whether a remote day met an employer necessity standard. Those are facts about your employment, and they sit alongside the ledger rather than inside it.

Planning notes

• Treat source and residency as separate exposures. Ending one does nothing to the other.
• Keep the working-day denominator with the same care as the in-state numerator; the fraction is only as good as its weaker half.
• Prepare the nonresident return before the resident one, since the credit depends on it.
• Check for a reciprocal agreement before doing any of this. Where one exists it removes the problem for wages entirely.
• Do not read withholding as liability. The two diverge routinely after a move, in both directions.