UK Residents With Danish Income Face a Harder Reporting Year in 2026

If you live in the UK and earn money in Denmark, the two tax systems you now deal with have drifted further apart this year. Denmark's personal tax reform took effect from January 2026, and the UK's own rules for foreign income changed in April 2025.

Neither change, on its own, is dramatic for most people. Together, they make it harder to work out what goes on your Self Assessment return, what relief you can claim, and which country gets first call on the tax.

That affects a small but growing group: UK residents on Danish payroll, contractors with Danish clients, people letting out Danish property, and UK directors of Danish companies. Some of them use a service to find an accountant in Denmark to handle the local filing, while their UK adviser handles the Self Assessment side. Many try to do both themselves.

Here is what has changed, and where the friction usually appears.

What changed in Denmark from January 2026

Denmark restructured its personal income tax bands at the start of this year. The headline is the replacement of the single top-bracket charge with a layered structure, including a new additional charge aimed at the highest earners, often referred to in Danish commentary as the "top-top" tax.

Reporting on the reform describes a middle band charged at 7.5%, a top band charged at a further 7.5%, and an extra 5% levy on income above a much higher threshold, alongside changes to personal allowances and the employment deduction.

Danish legal commentary on the introduction of the additional top-rate charge covers the same ground from a practitioner angle.

One caution before you use any of these figures. Danish thresholds are uprated annually and are quoted in DKK before or after the 8% labour market contribution depending on the source, which produces different-looking numbers for the same rule. Sterling equivalents also move with the exchange rate. The published rates from Skattestyrelsen are the figures to work from if you are calculating anything.

For most UK residents with modest Danish income, the new top layer will not bite. For a UK-resident director or contractor drawing a large Danish salary, the effective Danish rate on the top slice of income may be higher than it was in 2025, which in turn changes the amount of foreign tax credit available in the UK.

The UK taxes your worldwide income regardless

UK tax residence is determined by the statutory residence test, which looks at days spent in the UK alongside work ties, accommodation, family and previous residence. If you are UK resident and domiciled, or you no longer qualify for any special regime, your worldwide income is within the scope of UK tax.

That includes Danish salary, Danish self-employment profits, Danish rental income and Danish dividends. Danish tax having already been deducted does not remove the UK reporting obligation. It usually only affects the relief you claim.

There is a separate point for people who have recently moved to the UK. From 6 April 2025 the remittance basis was abolished and replaced with a four-year foreign income and gains regime for those who have not been UK resident in the previous ten tax years. If you arrived from Denmark recently, whether you fall inside or outside that four-year window changes the picture materially.

Why the 183-day idea is so often misread

The common belief is that fewer than 183 days in Denmark means no Danish tax. The reality is narrower.

The presence test sits inside the employment income article of the double tax treaty, and it is one of three conditions that must all be met before the UK alone keeps taxing rights. The other two concern who pays the salary and whether the cost is borne by a permanent establishment in Denmark.

Modern treaty wording also measures presence over any 12-month period beginning or ending in the tax year concerned, not over a single calendar year. Days can therefore be counted across a boundary in a way that catches people out.

The UK's arrangement with Denmark is given effect in domestic law by a statutory instrument, and the text of the double taxation relief order covering Denmark is publicly available. The precise wording of the relevant article, as amended by protocol, is what governs, not the general summary.

If your work is split between the two countries, the apportionment of employment income to Danish workdays is usually the decisive calculation, not a single day count.

Two tax years that do not line up

Denmark operates on the calendar year. The UK tax year runs from 6 April to 5 April the following year. One Danish year therefore straddles two UK years.

For the 2025/26 UK tax year, which ended on 5 April 2026, the online Self Assessment deadline is 31 January 2027. The paper deadline has already passed.

The mismatch matters most for foreign tax credit relief. You are claiming credit in a UK year for Danish tax arising on income that fell in a Danish year with different start and end dates, so the Danish figures usually have to be apportioned rather than copied across.

Timing of bonuses, dividends and one-off payments can shift income from one side of a boundary to the other in one system but not the other. A single year-end total from a Danish payslip summary will rarely be enough.

The SA106 pages are where this lands

Foreign income is reported on the foreign pages of the Self Assessment return.

Two points cause most of the errors. Credit relief is capped at the lower of the foreign tax paid and the UK tax due on the same income, so excess Danish tax is not refunded by HMRC. And credit is generally limited to the tax Denmark was entitled to charge under the treaty, not necessarily the amount actually withheld, which means over-withheld Danish tax has to be reclaimed from Denmark rather than recovered through the UK return.

Contractors face a different set of questions

For a UK freelancer invoicing a Danish client, the issue is rarely the invoice itself. It is whether the activity creates a taxable presence in Denmark.

The questions that tend to decide it include:

• where the work is physically performed, rather than where the client is based
• whether you have a fixed base or regular premises available to you in Denmark
• how frequently and for how long you travel there
• whether you operate through a Danish entity or an umbrella arrangement
• whether Danish employment law or payroll treats you as an employee rather than an independent contractor

A UK-based consultant who visits Copenhagen twice a year for workshops sits in a very different position from one who spends three days a week there for eighteen months. The second arrangement carries a real risk of limited Danish tax liability on the Danish workdays, and possibly of social security consequences depending on which country's system applies under the UK and EU coordination rules.

Social security is a separate track from income tax and does not follow the treaty. It is worth checking which system you contribute to before assuming the tax answer settles it.

Business owners carry the bigger exposure

If you run a UK company with activity in Denmark, the permanent establishment question moves from a personal issue to a corporate one. Fixed premises, local staff, a dependent agent concluding contracts, or sustained commercial activity can all create a Danish taxable presence for the business.

Once that happens, Danish corporate tax, payroll registration and VAT obligations can follow, each with its own registration and filing requirements.

Director remuneration sits awkwardly across the two systems. A UK-resident director of a Danish company may face Danish tax on director's fees under the specific treaty article dealing with directors, which often works differently from the general employment income rules. Treating the personal and corporate positions as separate exercises is where problems usually start.

The records that actually matter

The documentation burden is heavier than most people expect, and reconstructing it after the fact is difficult.

Useful records include a dated log of workdays by country, travel evidence such as boarding passes and accommodation bookings, Danish payslips showing the breakdown of withholding and the 8% labour market contribution, the annual Danish årsopgørelse, and contracts showing who bears the cost of your employment.

Keep the Danish tax year figures separately from any UK year apportionment you prepare. If HMRC queries a credit claim, the working is what gets asked for.

What professional help can and cannot do

Specialist cross-border advice is not cheap. Fees for dual-system personal filing can run well beyond ordinary UK Self Assessment costs, and for a straightforward case with one small source of Danish income the cost may outweigh the benefit.

Advisers also cannot make the two systems agree. They can establish which country has primary taxing rights, prepare the apportionments and file correctly, but they cannot remove the cash flow cost of paying Danish tax months before UK relief is claimed, and they cannot guarantee that a treaty position will go unchallenged.

The risks of getting it wrong are concrete rather than theoretical: late filing penalties in either country, interest on underpaid tax, disallowed credit claims, and in the business context a retrospective permanent establishment assessment covering several years.

The practical takeaway

The difficulty with UK and Danish cross-border income is not the headline rates. It is the plumbing: residence status, income source, workday apportionment, treaty articles and two reporting calendars that refuse to align.

For salaried employees with a clean single-country working pattern, the position usually stays manageable. For hybrid workers, contractors and company directors, the 2026 Danish changes add another variable to a calculation that was already fiddly.

With the 31 January 2027 online deadline for the 2025/26 UK return now under three months away, the Danish figures you will need are the ones worth gathering first.