Generally speaking (because I am unfamiliar with Kansas & Missouri) you should:

1. File a state return for your state of residency (Kansas) including 100% of your income, irrespective of where earned.

2. File in each and every other non-residency state in which you have "nexus". Nexus is sometimes differently defined however, entering a state & earning a wage there clearly qualifies. When filing in a non-residency state you would typically file as a "non-resident" & only declare the income directly derived from that state. On this basis you would likely file a non-resident tax return for 1999 in Missouri.

3. Typically, the following year you can take a credit on your resident return for foriegn state taxes paid the prior year; e.g. on your 2000 Kansas return there will be some form of credit apportionment / computation form that will give you 100% or some lesser percentage credit for taxes paid the prior year to Missouri.

TheBadger