I don't know that I would call it a "trick", but what I found helpful
was to introduce a "VAT Control" account which is my end of quarter
accrual (UK requires payment of sales taxes on a quarterly basis). So I
track VAT paid and earned as seperate ledgers, then clear these down to
zero at the end of each quarter (based on trial balance report, plus a
manual glance at the transactions report). Then I can simply enter my
VAT return based on this entry.
As an aside this also makes it simple to record the payment of sales tax
(which may have a timing difference), by recording the payment from the
control account
Happy to flesh this out on the wiki. I think it would be helpful for us