When you charge your customers sales tax, it posts to the Sales Tax Liability account (as a credit) in your chart of accounts. When you pay the collected tax to your state revenue department, you would post that payment to the same Sales Tax Liability account (as a debit) to reduce your liability. Generally, the sales taxes would not go through your P&L. Now if you are talking about sales taxes you pay on purchases, then in that case, I would post the taxes to the same expense account as the purchase. In other words, if you purchased office supplies on which sales taxes were charged, the entire amount including sales taxes paid would post to office supplies. Make sense?