Social secretariat notice period: when must you cancel?

Your social secretariat notice period is set by your contract, not by the law: at Acerta, SD Worx and Partena Professional, notice for a switch on 1 January 2027 had to go out by the end of June 2026 at the latest under their published terms. That date has passed. If you decide now, you aim for 1 January 2028 with those three, with notice sent by the end of June 2027 at the latest. Below you find, per secretariat, what the terms say, with a countdown to the next deadline.

Social secretariat notice period: the short answer per secretariat

Sources: the general terms of Acerta (version of 1 May 2026), SD Worx (version v202511) and Partena Professional (in force since 1 January 2025), and the websites of Securex, Liantis and Group S, reread on 18 October 2026. The dates for Acerta are our calculation: the terms count in working days and do not say whether sending or receipt counts.

The clock below counts down to the deadline for a switch on 1 January 2028, as it follows from the terms or the advice of each secretariat.

What the law says about giving notice, and what it does not

The law decides when you can change secretariat. How long you are bound and how you give notice, it leaves to your contract.

• Only at a new quarter. Article 31quater of the law of 29 June 1981 says that a mandate can pass to a new agent "only at the moment of the transition to a new quarter" (freely translated from Dutch). A switch therefore starts on 1 January, 1 April, 1 July or 1 October.
• One month of leeway at the NSSO. According to the NSSO guidelines for Mahis, your new secretariat can still start a mandate for a quarter up to 1 month after that quarter starts. Further back is not possible.
• The old secretariat reports the end. A secretariat must inform the NSSO of an employer's notice within 15 days.
• No endless tacit renewal. For contracts between businesses concluded or amended since 1 December 2020, a clause that tacitly renews a fixed-term contract without a reasonable notice period is presumed to be unfair (article VI.91/5 of the Code of Economic Law). The secretariat can prove otherwise. Have such a clause checked before you rely on it.

So a statutory notice period for a social secretariat does not exist. The periods below all come from the terms of the secretariats themselves.

Cancelling with Acerta, SD Worx and Partena: what their terms say

Three large secretariats publish their terms. They look alike: a first term of about three years, an end on 31 December and notice that must go out before 1 July.

Acerta

The general terms of Acerta (version of 1 May 2026) set up the cooperation for 3 full calendar years. After that it runs for an indefinite term. Notice is given by registered letter, with 6 months' notice starting on 1 July and ending on 31 December. The notice must be served "no later than 3 working days before 1 July". Article 4.3 adds: "Any other termination has no effect."

Business Centrum itself works with Acerta. If you are directly with Acerta and want a fixed contact with us, you do not change secretariat. We discuss with you how that works: see Acerta or Business Centrum.

SD Worx

The SD Worx affiliation agreement (version v202511) runs for 3 calendar years, plus the period until the next 1 January. After that it renews tacitly for one calendar year each time, unless a party gives notice "by registered letter through the post, which must be sent no later than 30 June". The contract then ends on 31 December of the same year. Here, the posting date is what counts.

Partena Professional

The organic regulations of Partena Professional, in force since 1 January 2025, bind you for at least 36 months, plus the rest of the starting year. After that they renew for twelve months each time. You give notice by registered letter, sent before 1 July, with at least 6 months' notice until 31 December. The postmark counts as proof. Under article 50, notice given after 1 July runs until 31 December of the following year.

Liantis, Securex and Group S: no published notice clause

Not every secretariat puts its contract terms online.

• Liantis publishes general terms with 13 articles, without a term or a notice clause. Under those terms, the signed quotation and the basic agreement take precedence, and those are not public. The period is therefore in your own documents.
• Securex writes on its website: "Give notice before 30 June to be able to switch in January of the following year", and that a contract runs "usually 3 years". That is advice, not contract text. We found no terms for the social secretariat.
• Group S publishes affiliation forms on its site, but no terms with a notice period for the social secretariat.

If you are with one of those three, or with a smaller secretariat, ask in writing until when your contract runs and by what date you can give notice.

Too late for 1 January 2027: what can you still do?

If the date has passed, there are three routes. Which one fits depends on your contract and on how much of a hurry you are in.

1. Read your own contract. The terms above are the standard. Your quotation or agreement may say something else, for example about the first term. What is in your contract takes precedence.
2. Leave earlier, for a fee. The terms provide for a fee if you break the contract. At Acerta that is the administration costs times the remaining months, with a minimum of € 971. At SD Worx 80% of the average recurring costs per remaining month, with at least 6 months of price. At Partena Professional 18 times the monthly management fees within the minimum term, or 12 times after a renewal. Work that out before you decide.
3. Plan the switch for 1 January 2028. Give notice before the date on the clock above. At Partena Professional, notice you send now runs until 31 December 2027 under the regulations. At Acerta and SD Worx, the terms do not say expressly what a letter sent today does. So ask for written confirmation of the date from which your notice applies.

Cancelling your social secretariat: the step-by-step switch

This is how a switch on 1 January 2028 runs, from the first decision to the last return of your previous secretariat.

1. Now: read your contract. Look for the term, the notice period, the date you give notice for, the form and the costs of leaving.
2. Before the summer: choose your new partner. Ask for a quotation for your actual staff. Our guide which social secretariat to choose lists the criteria, and the cost of a social secretariat helps you compare prices.
3. By the date on the clock at the latest: give notice by registered letter. State your client number, the contract you are ending and the end date. Ask for written confirmation and keep the proof of posting.
4. In the autumn: transfer the data. Your new partner requests the files: contracts, pay history, leave balances and the individual account per employee.
5. Around 1 January: the new mandate. Your new secretariat enters the mandate in Mahis, up to 1 month after the quarter starts. The old mandate then ends automatically.
6. In January: the last return of the previous secretariat. As a rule, your previous secretariat still files the DmfA for its last quarter, within 1 month after that quarter.

All the details on the transfer, the notice letter and the pitfalls are in our guide changing social secretariat.

Giving notice through Business Centrum: what we do for you

With Business Centrum you do not have to plan the switch alone. We work out the earliest date with you, contact your current secretariat and organise the transfer of the files. You sign the notice letter yourself, because it is your contract.

After the switch, you no longer do the work yourself:

• You send the hours, by email or form. We enter them.
• We do the Dimona declarations and follow up contracts and leave.
• You call or email your fixed contact directly in Ghent, who knows your business and your joint committee.
• Acerta is the recognised secretariat behind it, which files the returns and collects the contributions.

If you are mainly after a lower price, also read cheap social secretariat: it explains what a low price per payslip can cost you later.

Want to know until when you are tied to your current secretariat, and what a switch on 1 January 2028 means for your business? Business Centrum reads your contract with you and plans the start date.