I feel the best idea to me now is just put a low cost value on the form and put comment section that all the work is on landscaping, not the house structure itself. This translates to no or little increase in assessed value which means low annual property tax increase.
When I sell the house 25 years later I have to include my full cost of landscaping in cost basis and that part is governed by IRS. I have the receipt for the contractor and pictures showing the before and after work. They should be good to IRS side. So the cost basis for income tax purpose when I sells the house in future reflects the landscaping amount.
