Paying social security twice on the same salary is legal, common, and almost always avoidable - it happens because nobody applied for one certificate before the first payroll ran.
This guide covers the situations where dual liability actually arises, which agency issues the paperwork in each direction, and what happens if you sort it out late.
For how Dutch social security works in general - what you pay, what it buys, how to register - start with the Amsterdam social security guide.
When Dual Liability Actually Happens
Dutch national insurance attaches to residence and to work performed in the Netherlands, and most other countries claim contributions on the basis of where the employer is or where the employee is a national.
Dual liability is what happens when two of those tests point at different countries at the same time.
The four situations that produce it in practice are a short-term posting from abroad, employment by a foreign company while living in Amsterdam, working in two countries in the same month, and being a US citizen self-employed anywhere at all.
The last of those catches people who have thought about none of this: US citizens owe self-employment tax on worldwide self-employment income regardless of where they live, and the Dutch system charges its own national insurance on the same profit.
The 1990 US Agreement, In Both Directions
The United States and the Netherlands have had a totalization agreement in force since 1990, and it does two separate jobs that are easy to confuse.
First, it assigns you to one system so the same work is not charged twice.
Second, it lets you add periods of coverage in one country to periods in the other to reach a minimum qualifying record, which matters if you have neither forty US quarters nor a meaningful AOW accrual.
The general rule is that you are insured where you physically work, with a posting exception: an employee sent by a US employer to the Netherlands for an expected period of five years or less stays in US Social Security.
The certificate is issued by the country whose system you are staying in. That single sentence resolves the confusion most descriptions of this agreement create.
Staying in US Social Security while working in Amsterdam: your employer requests the certificate of coverage from the US Social Security Administration, and it is the document that exempts the Dutch payroll from national insurance.
Insured in the Netherlands and seeking exemption from US Social Security or self-employment tax: the certificate is form NL/USA 101, issued by the SVB‘s international secondment department in Amstelveen.
Keep the certificate rather than filing it and forgetting it; employers produce it against an IRS query, and self-employed Americans attach a copy to the US return every year it applies.
Three Situations, Worked Through
Posted from New York to Amsterdam for three years, US employer, US payroll. You stay in US Social Security, the employer obtains the SSA certificate before the assignment starts, and no Dutch national insurance is due on that employment.
You are still resident here for income tax and you still must buy Dutch health insurance, which the certificate does not touch.
Hired directly by an Amsterdam company on a local contract. You are in the Dutch system from day one, there is no certificate to obtain, and the 27.65 per cent national insurance charge is inside your income tax.
If you are a US citizen you keep filing US returns, but the totalization agreement means no US Social Security tax on that salary.
American freelancer living in Amsterdam with clients in both countries. You are insured in the Netherlands because that is where you work, and you apply to the SVB for form NL/USA 101 to switch off the US self-employment tax.
Without it you pay 15.3 per cent US self-employment tax on top of Dutch national insurance on the same profit, and the foreign earned income exclusion does not help, because it relieves income tax and not self-employment tax.
Inside The EU: Regulation 883/2004
For movement between EU and EEA states and Switzerland, the equivalent instrument is Regulation 883/2004 and the certificate is the A1, obtained from the SVB when the Netherlands is the competent state.
The default is again the country of work, with a posting exception of up to 24 months - shorter than the five years the US agreement allows, and the mistake most commonly made by people who know one rule and assume it is both.
If you work in two or more member states, you are insured in your country of residence provided you perform a substantial part of the work there, which is taken as at least 25 per cent measured by working time or by pay.
Fall below 25 per cent at home and you are insured where the employer has its registered office instead.
Cross-border home working has had its own framework agreement since July 2023, under which teleworking from your country of residence for a foreign employer can stay under 50 per cent without moving your coverage - but only where both states have signed and both parties apply for it.
What Happens If You Get It Wrong
Certificates can be issued retroactively, and both the SVB and the SSA regularly do so, which means a posting that started without one is a correctable problem rather than a lost one.
Contributions wrongly paid to the Dutch system are refunded through the Belastingdienst once the correct certificate is on file, and a wrongly assessed year can be reopened.
The cost of late correction is time and the accountant’s fee, not the money itself, and it rises steeply once a year has closed and a return has been filed on the wrong basis.
Where the answer is genuinely unclear - split roles, two employers, a posting that keeps being extended - get it decided before the first payroll rather than after, because the assignment rule follows the facts you set up rather than the label on the contract.
Frequently Asked Questions
Who issues the certificate of coverage?
The country whose system you remain insured in: the US Social Security Administration for a US posting to the Netherlands, the SVB for form NL/USA 101 when you are insured here.
Applying to the wrong agency is the most common cause of delay on this step.
How long can a US posting last?
Five years, under the 1990 agreement, after which Dutch coverage takes over.
Within the EU the equivalent posting limit is 24 months, so do not carry one rule across to the other.
I am a self-employed American in Amsterdam. What do I do?
Apply to the SVB for form NL/USA 101 and attach a copy to your US return each year.
Without it you pay 15.3 per cent US self-employment tax on the same profit that Dutch national insurance already charges, and the foreign earned income exclusion will not offset it.
Does the certificate exempt me from Dutch health insurance?
No, and this is a separate obligation with its own deadline: a basic policy from a Dutch insurer within four months of registering, backdated to arrival.
The average basic premium is about €159 a month in 2026, with a €385 compulsory excess.
Can I fix a posting that started without a certificate?
Yes - both agencies issue retroactively, and contributions paid to the wrong system are refundable once the certificate is on file.
The correction gets harder after the tax year closes, not impossible.
I work in the Netherlands and Belgium. Where am I insured?
In your country of residence if at least 25 per cent of your working time or pay falls there, and in the country of the employer’s registered office if it does not.
The A1 certificate from the SVB is what records the answer.
