if multiple people are on a lease as tenant and one doesnt pay there portion of rent are others Liable?

Yes.  Unless the lease provides otherwise (it won't), each tenant has agreed with the landlord to be responsible for the full rent.  While the tenants may have agreed between themselves that they would each be responsible for a portion of the rent, that agreement doesn't affect their obligation to their landlord.  However, any tenant who pays more than his agreed share can sue those tenants who paid less for the difference. In some jurisdictions (not sure about Maryland), you would have a duty to mitigate damages.  In other words, you couldn't sue the absent tenant for her missing rent unless you had tried to rent the space to others and couldn't.