When Do Car Insurance Rates Go Up? 
I agree with Cathy , but also offer one other major reason rates go up . Insurers are pricing a product before they know their cost . It something like building a spec house for sale at $ 300,000 with out knowing that the purchaser is going to require all hard wood floors , a finished basement and a three car garage . Had you known you would have priced your product at $ 400,000 . This is some of the dilemma of insurers . Thy can look at historical outcomes and yet may not see a trend developing before it happens . The reason most auto insurance is sold in Six month terms in the US , is that it often takes a minimum of one year for the carrier to realize rate level on all customers in a certain state and rate filing . Let me give an example : If company A sees it needs rate increase on its TX auto insurance business and puts that rate into effect after state approval on July 1,2014 it will take a full six months to raise the rate level to the new level for the last customer whose policy incepts on 12/31/2014 . Then it takes the company another 6 months to earn the premium for each of those customers . It has to set aside some money in case you decide to move your business , as well as keep reserves for accidents that have occurred or are known to be likely to occur in the future.So in a full year at 7/1/2015 the company has realized the effects of its rate filing in the state . If it now needs more funds , it will take the same 12 months to fully earn that premium . So in effect you can see that the process of getting an adequate rate for an insurers losses and expected losses is at least a year on six month polices and double that to two years to achieve the rate level on annual policies . That said , recognize that your rates can go up annually in a 12 month policy because of a company 's filings and go up as much as every six months for an insurer who uses 6 moth policies.So , all that said , you do n't control the pricing that is an aggregate need of the insurer but you can better protect yourself by buying a 12 month policy . Lock in a rate level . If you do not change the exposure -LRB- new car or new operators and such -RRB- , you will have locked in rate for one whole year . So my advice is to seek out an insurer that writes annual policies if available . 