The Co-signer will remain responsible for the entire term of the lease, including any renewal and will not be released without written consent of the Landlord/Property Management Company. The Co-signer agrees to payment of rent and any monetary damages suffered by the Landlord/Property Management Company.
The most common example is a parent co-signing for their child's first apartment since the child has no rental history. Other examples include co-signing an apartment for a significant other who doesn't live with you or for an unemployed family member.
Your options are to find someone who can co-sign, try to explain to this management company that you don't have a co-signer and see what their response is, or try to rent from a smaller local landlord/management company where you can talk to them on a personal level.
Joint tenancies In this situation, as a guarantor, you are likely to be responsible for whatever any of the joint tenants owe the landlord, not just what the tenant you are helping may owe. You may also be responsible for any damage caused by other tenants, not just the one you're wanting to help.
Choose someone you trust to be there if you need them. That person also shouldn't harbor hard feelings against you if you were to need their help. Family members or close friends are a good starting point for finding a co-signer.
Go To Your Landlord or Management Company For example, property owners in California must: Provide a copy of the rental agreement or lease to the tenant within 15 days of its execution by the tenant.