I am not an accountant and I do not even play one on TV. So, to get answers specific to your question you should consult an accountant. However, in general, you can do a 1031 Exchange to defer capital gains tax. What this means is that if you have an income producing property, ie your california condo, you can sell it and purchase something of equal or greater value that will also produce income, and defer the tax. So if you sell your condo and buy a house in Austin that you rent out and you pay $375K for that house then you would not have to pay a capital gains tax at this point. If you want to pocket the cash you have and buy something for 225K then the 150 K you pocket would have some tax due, depending on what the actual gain is on the property. If you bought the condo fro 375K or more than there is no gain and you probably don't owe tax. However, if you bought it for less than 375K and do not use the entire 375K to buy a new rental property then there will be some taxes owed. Again, you would need to speak with an accountant to determine how much. You will have to identify a new property in 45 days from close of escrow on the condo, and close escrow on the new property within 180 days of selling the the condo.
If you are going to buy a house in Austin to live in, not as an investment then you will not be able to defer the gain.
Also, if you lived in the Ca condo for 2 of the last 5 years then you can use your homeowner exemption to not ever pay tax on up to $250K for a single or $500K for a married person, even if it was rented out for 3 of the last 5 five years.
I hope this helps!