A lease personal guaranty is a personal guarantee to uphold the terms of a lease that is under the name of another person. The person making signing the guaranty (“co-signer”) makes the pledge that if the tenant cannot pay for any portion of the lease, that the co-signer agrees to pay the landlord. This is common for tenants with low credit or cannot afford to pay the monthly rent. Whatever the reason, it gives the landlord a higher probability that rent will be paid each month and on time.