The option of borrowing also potentially re-introduces adverse work incentives among unemployed individuals with negative account balances. In order to ensure that individuals with negative balances do not withdraw from the labour market or move into informal work, pension contributions could be used as collateral (Stiglitz and Yun, 2005).38 This option has not been implemented anywhere yet. This approach is likely to involve more redistribution than the UA-plus-borrowing alternative but less than in a pure system of UI.