The AHV top-up, and how not to be surprised by it.

During the year SVA Zürich bills you advance payments. It works them out from the income it expects, normally the one from your last contribution ruling.

You pay four times a year, each within 10 days after the end of the quarter: on 10 April, 10 July, 10 October and 10 January. What counts is when the money reaches SVA, not when you send it. If your contributions are CHF 3'000 a year or less, SVA can set longer periods, up to once a year.

What you really owe is only clear once the tax office has made your assessment final and reported your income to SVA. SVA is bound by that figure.

Then it settles up. If you paid too little, the top-up arrives, payable within 30 days. If you paid too much, you get it back or it's offset. SVA may also bill you the difference before the tax office reports.

The interest is 5 % a year, counting every month as 30 days. It applies in three cases:

• An advance payment doesn't arrive within 30 days after the end of the quarter. Then from the end of the quarter.
• The top-up bill isn't paid within 30 days. Then from the date of the bill.
• The 75 % rule: if your advance payments were at least 25 % below the contributions you actually owe, and the difference isn't paid by 1 January of the year after next, interest runs from that day. For 2026 that's from 01.01.2028, even if the bill only comes later.

With the third rule, waiting doesn't help. The final bill can arrive after that date, and by then the interest is already running.

Lea is self-employed in Zurich in 2026. SVA expects a profit of CHF 36'000 and bills her CHF 600 a quarter, CHF 2'400 for the year.

By the end of October Lea already has a profit of CHF 46'400. On the 2026 scale she owes CHF 3'465.60 in AHV, IV and EO on it, plus CHF 173.30 in SVA admin fees, CHF 3'638.90 in total.

Her advance payments cover only 66 % of that. If nothing changes, a top-up of about CHF 1'240 follows, and because she's below 75 %, interest runs on it from 01.01.2028 until it's paid.

Her profit is 29 % above what SVA expects. From 25 % she has to report it. She writes to SVA now. SVA adjusts the remaining advance payments, and Lea can ask to be billed early for whatever is still missing.

Leaflet 2.02 has its own example: advance payments for 2024 of CHF 9'500.40, final contributions of CHF 30'400, bill dated 13.01.2026. Because the advances were below 75 %, the 1 to 13 January 2026 alone costs CHF 37.75 in interest.

If during the year you notice your income is 25 % or more away from what SVA expects, you have to tell SVA. That works both ways, up and down. SVA then adjusts the next advance payments. After the year ends it doesn't change anything retroactively; it bills you the difference instead.

A short message is enough, by email or through SVA Zürich's contact form. Include your name, your AHV number and the profit you expect for the year.

Zettelio keeps comparing your advance payments with what you owe on your payments. When the gap gets big, it shows you a ready-made message for SVA.