The special agreement is a situation assimilated to inscription, deriving from a voluntary agreement between the subscriber and the Social Security General Treasury, with the subscriber's obligation to pay the corresponding contributions at their own expense, in order to pay contributions and be entitled to the benefits derived from the contingencies covered in the special agreement.

However, there are exceptions, such as the ERE agreements whereby the contribution is paid by the company until the worker included in the ERE reaches 61/63 years of age, or the agreements for non-professional carers, which are currently financed by the IMSERSO.

The purpose of concluding a special agreement with the Social Security is to pay social security contributions in order to obtain coverage for the common contingencies protected by the agreement.

These contingencies are:

• Permanent disability due to common disease and non-work-related injury
• Death and survival resulting from common disease and non-work-related injury
• Retirement