EU Cross-Border Social Security & A1 Certificate Simulator

Determine applicable social security jurisdiction for cross-border teleworkers, test 25%/50% thresholds, and model payroll contribution impacts.

Cross-border telework: which social security country (25% or 50%)?

An employee who spends at least 25% of their working time in their country of residence is, in principle, insured in that country (Regulation 883/2004). Since 1 July 2023, the framework agreement on cross-border telework lets them stay insured in the employer's country as long as telework stays below 50%. The tool applies one rule or the other and works out the contributions under the resulting scheme.

The two rules applied

Regulation (EC) No 883/2004 (Art. 13) attaches an employee working in several states to a single scheme. If at least 25% of their working time or pay falls in their country of residence (the substantial-activity threshold, Art. 14(8) of Regulation 987/2009), that country's social security applies. The tool turns your telework days into a share of a five-day week: 1.5 days is 30%, 2 days is 40%.

With the framework-agreement box ticked, the employer's scheme is kept as long as telework in the country of residence stays below 50%; at 2.5 days (50%) the tool switches to the residence scheme.

Example

Resident in France, employer in Luxembourg, €75,000 gross, 2 telework days (40%). Under the framework agreement the Luxembourg scheme still applies: €9,375 employer contributions (12.5%), €9,375 employee contributions, €65,625 net before income tax and a total employer cost of €84,375. Without the agreement, 40% exceeds 25%, so French social security applies: €31,500 employer (42%), €16,500 employee (22%), €58,500 net and €106,500 total cost, i.e. €22,125 more for the employer.

Limits

  • Each country uses one flat rate with no ceilings or reliefs: indicative values, not verified.
  • The threshold is really assessed over the next 12 months and may be based on pay; the tool only looks at weekly time.
  • The agreement is not automatic: the employer files a request under Article 16 of Regulation 883/2004 with the employee's consent. It only covers telework between two signatory states; every country offered here has signed, Italy since 1 January 2024.
  • Income tax, governed by tax treaties, is not calculated.

This is an estimate and does not replace advice from the competent institution or an adviser.

Sources and dates: Regulation (EC) No 883/2004, Arts. 13 and 16; Regulation (EC) No 987/2009, Art. 14(8) (25% threshold); multilateral framework agreement on cross-border telework, applicable since 1 July 2023, signatory list kept by the Belgian FPS Social Security as depositary (checked 14/10/2026).

Frequently Asked Questions

How many telework days can a cross-border worker do without changing social security country?

Under the general rule, less than 25% of working time in the country of residence, i.e. one day a week. Under the framework agreement applicable since 1 July 2023, the limit rises to below 50%: up to 2 days out of 5, whereas 2.5 days switch the worker to the residence scheme.

What is an A1 certificate?

It is the form certifying which social security legislation applies to someone working in several EU or EEA countries or Switzerland. The employer requests it from the institution of the country whose legislation applies and shows it during an inspection; without it, the country of work may claim its own contributions.

Does the telework framework agreement apply automatically?

No. The employer has to file an exception request under Article 16 of Regulation 883/2004, with the employee's consent. The agreement only covers connected telework carried out in the country of residence, where both that country and the employer's country have signed it.

Do these rules apply to a France-Switzerland cross-border worker?

Yes. Regulation 883/2004 applies to Switzerland through the agreement on the free movement of persons, and Switzerland has been a signatory of the framework agreement since 1 July 2023. The 50% threshold therefore covers a French resident employed by a Swiss company, provided the employer files the request.

Is this tool really free?

Yes, all tools on Kristools are 100% free and accessible without registration.

Is my data protected?

Yes. All processing is performed directly and securely inside your browser. No personal data is sent to our servers.