What counts as a workday for splitting my income?
Generally a day on which you actually worked, rather than every day on the calendar, and the count usually excludes weekends, public holidays and leave unless work was in fact performed. The denominator matters as much as the numerator: a split is a fraction, and choosing a different basis for total days changes the answer without changing a single fact. The countries involved may not define it identically, which is why the underlying record should show where you were and whether you worked, day by day. From that record either definition can be applied. From a summary, neither can.
How do I prove where I was working on a given day?
With documents created at the time rather than a reconstruction. Boarding passes, passport entries, hotel and card statements, calendar exports, timesheets and internal travel approvals all carry dates and places, and together they usually settle a day. Single sources have gaps: a passport does not stamp every crossing, and a calendar records intentions rather than events. Build the record from several sources, note where they conflict, and resolve the conflicts before filing rather than afterwards. A day that cannot be evidenced should be treated conservatively and flagged, not quietly assigned to whichever country is cheaper.
Do travel days count in both countries?
A day spent partly in each is the awkward case, and the countries involved may treat it differently, one counting a part day as a day of presence and the other apportioning or ignoring it. Because a handful of such days rarely moves the answer much, the sensible approach is to record them accurately and apply each country's own rule to the same record, rather than adopting a single convention and hoping both accept it. Where travel days make up a large part of the year, which happens with commuters, their treatment stops being a detail and should be settled before the year ends.
Can I just use my months of residence to split my salary?
It is a common shortcut and it usually gives the wrong answer. Residence describes your status; sourcing describes where the work was done, and the two diverge whenever you travel for work, take leave, or move partway through a pay period. Salary earned on days worked in one country is generally sourced there whatever your residence, and bonuses are worse, because the period they relate to often has nothing to do with the year they are paid in. Use the workday record. If there is no record, building one is the first piece of work.
Which period do I count days over for a bonus?
The period the bonus was earned over, not the year it was paid in. That period is set by the plan or the employment terms, so the document is the starting point, and it commonly spans a move or a change of employer. Once the window is fixed, the split is the same exercise as for salary: workdays in each country across that window. Equity follows the same logic over a longer window. Getting this wrong is the most common reason a return and a payroll slip disagree, because payroll almost always reports against the payment date.
The tax office wants my travel record, what are they asking for?
Usually the underlying evidence rather than the schedule you filed. A spreadsheet of days is a conclusion; the request is for what it was built from, day by day, for the period in question. Provide the record in a form that can be checked against the source documents, with the sources referenced, and explain the treatment of any day that was estimated. Where a day is genuinely uncertain, say so. A record that presents every day as certain, when some plainly were not, invites a wider look at the rest of it.
What happens if the two countries disagree about which of them can tax me?
The treaty has a procedure for exactly that. You apply to the competent authority in your residence country, which takes the case up with its counterpart, and the two negotiate a position that removes the double taxation. Some treaties add binding arbitration if they cannot agree. It is slow and it runs on documents, so the practical work is preserving the record and filing protective claims while the clock runs. See our treaty work.
Do American citizens living abroad have to pay taxes?
American expats and green card holders need to file US returns for life, and many of them pay little or no US tax once the relief is applied — but the filing is what unlocks the relief, so the two questions have different answers. The exclusion for foreign earned income, the credit for foreign tax already paid and the treaty between the two countries between them usually leave the total at roughly the higher of the two countries' tax rather than the sum. Skip the return and none of it applies. See Americans abroad.
