How to Calculate Project Deadlines Across EU Countries

Why "10 Business Days" Is Not a Universal Number

In the EU, a "business day" means a day that is neither a weekend nor a public holiday. The problem is that public holidays are set at national — and sometimes regional — level. There is no harmonised EU business day standard. The practical consequence: a 10-business-day window starting 1 May 2026 closes on 18 May in Germany and on 19 May in France.

The difference is a single day in this example, but it comes from a real divergence: France observes Victory in Europe Day on 8 May (a Friday), which Germany does not. Across a longer window — say, 30 business days through May — the gap between a French and German deadline can reach two to three working days.

Step-by-Step: Calculating a Cross-Border Deadline

Step 1: Establish the start date and Day 1

Identify whether Day 1 is the trigger date itself or the following business day. Most EU legal frameworks, including the Late Payment Directive, use the day after the triggering event as Day 1. Commercial contracts vary — read the clause carefully. A common source of error is double-counting: if the invoice date is 1 May, the first day of the payment period is 2 May under the directive, not 1 May.

Step 2: Identify which country's calendar governs

If the contract specifies a calendar, use it. If not, apply the calendar of the country whose law governs the contract. If the governing law is ambiguous, use the country of performance. For project planning (as opposed to legal deadlines), consider running both calendars and using the later date.

Step 3: Pull the public holiday list for each relevant country

For 2026, the key EU-wide moveable dates are: Good Friday 3 April, Easter Monday 6 April, Ascension 14 May, Whit Monday 25 May. Country-specific additions layer on top. Note that several holidays in 2026 fall on weekends — German Unity Day (Saturday 3 October), Assumption (Saturday 15 August in most Catholic countries), All Saints' Day (Sunday 1 November) — and these do not add working-day closures despite appearing on the holiday list.

Step 4: Count sequentially, excluding weekends and public holidays

Do not multiply weeks by five and subtract holidays — that calculation breaks whenever holidays fall on weekends, because a Saturday holiday reduces the gross total without removing a weekday. Count day by day: if the day is a Monday–Friday that is not a public holiday in your calendar, it is a business day.

Step 5: Confirm the deadline date

Record the date on which you reach your nth business day. That is your deadline.

Step 6: Document and communicate

Write the deadline as a concrete calendar date alongside the business-day clause. For example: "10 business days from invoice date, per the German statutory holiday calendar (North Rhine-Westphalia) — equivalent to 18 May 2026." This prevents both parties from recalculating independently and arriving at different answers.

What Happens When Both Countries Have Different Holidays?

You have three practical approaches:

The union calendar approach is most appropriate for collaborative project planning. If your team in Berlin and your client in Paris both need to be available, any day that is a public holiday in either country is effectively a non-working day for the project.

Practical Example: 10 Business Days from 1 May 2026 (Germany vs France)

Starting point: 1 May 2026, Labour Day. Public holiday in both Germany and France — this is Day 0 in both calculations.

Germany (nationwide calendar):

German deadline: 18 May 2026

France (national calendar):

French deadline: 19 May 2026

A German company expecting delivery on 18 May, under a contract governed by French law, has no valid claim for lateness on that date. The French supplier is on time at 19 May. The inverse is also true: a French company operating under a German-law contract would need to deliver by 18 May. The difference traces entirely to Victory Day.

Common Mistakes to Avoid

Assuming national holidays apply uniformly within a country. In Germany, Corpus Christi (4 June) is a holiday in Bavaria, Baden-Württemberg, North Rhine-Westphalia, and several other states — but not in Berlin, Hamburg, or Bremen. A Berlin deadline and a Munich deadline calculated from the same start date will differ if the window covers 4 June.

Ignoring holidays that fall on weekends. A holiday on Saturday does not shift to the following Monday in most EU jurisdictions. It simply does not count as a working-day closure. Do not subtract it from your business-day count.

Mixing calendar days and business days. Some payment terms use calendar days (the EU Late Payment Directive defaults to 30 calendar days), others use business days. A 30-calendar-day term starting 1 May ends on 31 May regardless of holidays. A 30-business-day term starting on the same date could end in late June.

Not specifying the calendar in the contract. This is the root cause of most cross-border deadline disputes. Without a named calendar, both parties calculate independently and often arrive at different dates. Always specify.

When Regional Calendars Make a Bigger Difference

For contracts involving German counterparties, specifying the federal state matters. Bavaria observes Corpus Christi (4 June, Thursday), Assumption of Mary (15 August, Saturday — no working-day impact in 2026), and All Saints' Day (1 November, Sunday — no working-day impact in 2026), in addition to the 9 federal holidays. A 30-business-day deadline running from 1 May through the summer will land on a different date in Munich than in Berlin.

In Spain, autonomous communities add up to four regional holidays on top of the 8 national ones. A contract referencing "Spanish business days" without specifying a community is ambiguous — and Spanish courts have had to interpret this.

The EU Biz Tools Working Days Calculator handles cross-border deadline calculation for all EU countries, including German state-level holidays and regional exceptions. Enter your start date, select the country (and state where applicable), and get the exact deadline date — no manual counting required.