A married woman who works as self-employed in her joint business with her husband, is subject to the obligation to register at the National Insurance Institute and pay insurance contributions. Couple who work in a joint business can split the business income between them and pay insurance contributions each of them on their own share, provided that the split between them is from 1/3 to 2/3 of overall income. If one of the spouses has incomes not related to the joint business, the earner of such income is not able to attribute to his share but 1/3 of the joint business incomes.