It would be nice if there was a direct means of redeeding land from one group to another.
I am not sure how often this occurs but the current system is vague in it's process and inadvertantly can cause someone's tier to increase.
My understanding is that the current process is as follows:
1. Decrease contribution to group A to 0.
2. Sell your land to yourself.
3. Redeed with full contribution to group B.
If you don't do step 1 before repurchasing your own land, your tier level could increase depending on the size of the parcel. (The system does warn you that your tier level will increase when appropriate but the assumption is that it will net to 0 since your purchasing your land from yourself).
I went from $40 land use fees to $75 by not doing step 1 on an 8448 size parcel.
Even though I was able to go into my account setup to lower the tier, it still reflects the increased peak usage for the month which I will be billed accordingly.