So, it's going to be hard to help you from the information you've supplied.
You can research the assessment at http://www.DallasCAD.org
and you can pay them on-line at http://www.DallasCounty.org/applications/english/proptax_app/tax_in
OR in person at one of the offices, for example, 500 Elm Street, Dallas, TX 75202 or 408 S Beckley Avenue, Dallas, TX 75203.
Remember taxes are due by 1/31 of each year without penalty. On 2/1 there's a big increase in what you owe. So, you have time.
which means that they are collecting the TAXES and INSURANCE with the PRINCIPLE and INTEREST and paying those bills for you:
Do you know that you do not have this feature?
If you have a Mortgage Statement handy, it will show how much was paid for what.
If you are looking for more information;
goodluck, God bless and have a Happy Thanksgiving