The license plates in Kansas expire based on the first letter in the last name of first person on the title.

Last name begins with	Tag expires at midnight on
A	February 28 (or 29)
B	March 31
C-D	April 30
E-F-G	May 31
H-I	June 30
J-K-L	July 31
M-N-O	August 31
P-Q-R	September 30
S	October 31
T-V-W	November 30
U-X-Y-Z	December 31

Trailers and heavy trucks are registered on a calendar year.  The tag expires on December 31st.  They can be renewed anytime after the first of the year following and must be paid by February 28th (29th) to avoid penalties.