Sounds like you're just given a payment delay of 2 years, which seems a pretty good deal to me. Put the money in a bank account for 2 years, let it earn interest, then pay it down.
It's a terrible deal because you have to pay your top marginal income tax rate (37.5-50%) of your "good" year on that money that isn't even yours, which you otherwise wouldn't, as social security payments are tax-deductible. In the "bad" year 2 years later, you obviously can deduct it, but as your earnings are low, you're in a lower tax band or even wouldn't be paying any tax at all (which is the case for me). So in my case this loses me thousands of Euros.
In "down" years you're also forced to lend them money that you'll get back 2 years later. I fail to see how this is a good deal.
Even if the tax bands happen to coincide, it's pretty hard to find even fixed-term savings accounts that earn more interest than inflation these days. Even my pension fund is actively losing money. (of course I don't have a choice about paying into it)
