Not sure how it works in Bulgaria, but over here in the Netherlands if your income is lower than some level you can (with some conditions) apply for unemploymen

Not sure how it works in Bulgaria, but over here in the Netherlands if your income is lower than some level you can (with some conditions) apply for unemployment benefits that will include enough money for the social security taxes. This is a bit roundabout (why not just withhold the social security money from the benefits in the first place?), but such are the joys of a complex tax system evolved over multiple centuries.