Thank you for explanation. Most of your assumptions are right, but I think there is some misunderstanding about purpose of tax report. Under VAT regulations as introduced in many countries (and I think this apply also to other taxing schemes), every tax payer has to maintain tax registers, for all transactions subject to tax. Both bank payments and bank deposits (due to tax refunds) from/to tax authorities are not taxable transactions, so should not appear in tax report. At any time, current balance on tax account shows current company tax duties.
Basically most amounts in tax report will mirror sales and purchase invoice transactions, but sometimes there are other more specific GL transactions which should be included in either input or output tax registers. For example sometimes company can lawfully withdraw some part of tax related to overdue payments from customers. This can be recorded as journal entry moving tax between input/output and some clearing GL account, and this should be visible in tax report.
So in other words, tax report is official document, which calculates company's tax duties for selected period. Sums from the report are then declared to tax authorities, and company pays (or receive) tax with Bank Payment/Bank Deposit which is outside scope of tax report.
Summarizing, third of your assumption is not valid. But if there is any scenario when assumptions 1,2, or 4 seems still not work, we have aug which should be fixed.