If someone else intends or has claimed the Taxpayer as a dependent, the Taxpayer must check the box marked "Check here if the Taxpayer can be claimed as a dependent on someone else's return". This check box can be found in the Personal Information section of your account. The person claiming the dependent will receive the benefit of the additional exemption, not the individual that is listed as the dependent.
Married Filing Jointly
If you are filing a return as Married Filing Jointly and someone else intends to claim either the Taxpayer or the Spouse on the return as a dependent, you must check the same box. In most cases, if you are Married Filing Jointly, you either claim both exemptions for the Taxpayer and Spouse or, if someone is claiming one of the persons as a dependent, you claim neither exemption. By checking the box indicating that someone is claiming you or your spouse, you will elect to claim neither exemption.
Note: In general, someone else should not be claiming you or your spouse (if you are filing Married Filing Jointly) as a dependent unless your return is only a claim for a refund and there would be no tax liability for either you or your spouse if you filed separate returns.