What the retroactive buy-back allows
Until now, an unused 3a year was lost for good: you could not make up a forgotten contribution. The new scheme changes this by allowing you, under conditions, to fill past gaps with an additional — and also deductible — payment. It is an opportunity above all for those who had periods without contributions (early career, studies, irregular income).
The conditions to meet
The buy-back follows precise rules. You must be enrolled in 3a and have earned income subject to AHV during the years concerned. Above all, a buy-back is only possible once you have paid the ordinary ceiling for the current year; the retroactive top-up is added on, within an annual limit. Years that are too old or predate the scheme cannot be bought back.
What is the tax benefit?
Like a standard 3a contribution, the buy-back lowers your taxable income in the year it is made. Well managed, it lets you smooth an income peak (a bonus, a sale, an exceptional year) and absorb a one-off tax charge. The effect is stronger the higher your marginal rate in the year of the buy-back.
Should you go for it?
A buy-back makes sense if you have the savings capacity and a clear provision or optimisation goal. It makes less sense if your liquidity is already tight. As always with the third pillar, the trade-off depends on your horizon, your canton and your tax rate: it pays to run the numbers before deciding.