A major advantage of pillar 3a is the tax savings. Payments can be listed in the tax return under «deductions», which leads to a reduction in taxable income. If you have little income and therefore pay relatively little tax, it is not so interesting to pay into pillar 3a. It is more interesting to make a deposit in the years when you earn full. In this case, the tax deduction is more effective and you save the most tax.
3a Retirement Savings Foundation