There are several benefits to being a Teaching Assistant. All benefits listed below can be discussed with the Mathematics Department Payroll Manager.
Graduate employees have a choice of several HMOs in the Dane County area as well as a Standard Plan (allows you to see any doctor of your choice, etc.) The insurance does include some limited dental coverage. There is a monthly premium taken from your paycheck, which is set by the State of Wisconsin. Note: Plans change their rates every year and the cost could change yearly. It is possible to change plans each year in October.
Any TA with an appointment of 33.3% or greater is entitled to have their tuition waived. Thus, if you are employed by the department, you should only have to pay segregated ("seg") fees, which amount to around \$500-600 per semester for full-time non-dissertators and around $250 per semester for dissertators. (It depends upon the number of credits you take.) See the Registrar's website for more detailed information about segregated fees. (Be sure to choose "Graduate" under student career.)
Your first paycheck will be October 1. First-time TAs can get an advance on part of this amount, check with the Payroll Manager for more information. Note, however, that this advance is only available to people starting their very first appointment at the UW.
The contract with the University gives TAs sick leave of six days per semester, not more than 12 days per year. If you need to miss teaching your section(s) because of illness or injury (yours or someone in your immediate family), you can choose to use this sick leave. Ordinarily, especially for short illnesses, instead of taking sick leave people will simply find an unpaid substitute, which is acceptable to the Course Supervisor (i.e. lecturer) and the Faculty TA Coordinator, or fulfill duties at a different time or by other means, which are acceptable to the teaching supervisor.
However, you should be aware that the option of taking sick leave exists. If you need to take sick leave, which cannot be arranged in advance, call the Department's Receptionist (608-263-3054) AND contact the Graduate Coordinator, Kathie Keyes, firstname.lastname@example.org, (608) 263-8884, as soon as possible. Taking sick leave does not require you to find a substitute. However, you should notify the TA Supervisor as soon as possible and provide assistance to identify a substitute. Canceling class is not an option.
If you need to miss classes due to a reason other than being sick (e.g. attending a conference), you need to provide your Course Supervisor and the TA Coordinator (Gong) with a class coverage plan. Canceling classes is not acceptable.
The teaching contract gives students other financial benefits, which are rarely taken advantage of by graduate students but are definitely available to those who want them. They include Supplemental Dental insurance, Vision Insurance, Domestic Partner benefits, Employee Reimbursement Accounts (also called Flex or Medical Spending accounts), retirement savings accounts (Wisconsin Deferred Compensation and others), life insurance, and accidental death and dismemberment insurance. If you are interested in these options, see http://benefits.wisc.edu/grads and the Math Department Payroll Manager.