Generally a tank should be pumped every 2 to 3 years. The size of the tank and water consumption will also help determine this. Wisconsin code dictates the tank should be pumped when the sludge/scum layers reach 1/3 of the total capacity. The service technician can evaluate your tank and recommend a pumping schedule based on his observation.
The septic tank always looks full. This is how it is supposed to be working. If the level is over the pipe then it indicates a blockage or saturated condition. It should then be pumped out and problem diagnosed before anything more costly occurs.
Remember, your drains are not trash cans. Flush only human waste, a moderate amount of toilet paper, and bath, dish, and clothes washing water. Don’t dump grease, coffee grounds, cigarette butts, sanitary products, chemicals, medications, inert materials (carpet lint, wrappers, etc.), or toxic substances down the drain.