When you co-sign a lease, it will usually specify what the co-signor agrees to. There may also be other documents (e.g., a co-signor agreement) outlining what you agree to. If you assume all of the tenant’s liabilities and responsibilities, you will be responsible for them. Before co-signing a lease or any other document, know what you are signing up for. Even if you are just trying to “help” someone out, you can be responsible for paying the rent (and possibly more) if they don’t meet their obligations. If you have any concerns about your obligations as a co-signor, seek legal advice.