My background is Ireland, where there's a general requirement to self-assess an accurate value; you're not specifically required to take offers into account but you're not required to ignore them either, it's more of a "you should assess all the information available and come up with an accurate valuation" type law, with the specifics being left to interpretation. https://www.revenue.ie/en/property/local-property-tax/valuin... has a bit about the process.