How To Write A Property Tax Protest Letter . Go in with a realistic answer. Filing the protest the deadline to protest this year’s appraisal is may 15, (earlier if filing online). Tax Protest Letter Template Collection Letter Cover Templates from ntgj.org If a tax exemption is sought, the listed tax exemption needs to be mentioned. Be aware of the online offers from the appraisal district. Some steps to take before sending a property tax appeal letter are: