If you live in an noncommunity property state and have owned an asset jointly with your spouse since before 1976, transferring the asset to your living trust could cause your surviving spouse to pay more in capital gains tax if he or she decides to sell the asset after you die.
If the asset is your personal residence, this would not be a problem unless the gain is more than $500,000. But it could be a problem for other assets like farmland, commercial real estate or stocks. If you think this might apply to your situation, be sure to check with your tax advisor or attorney before you change the title to your trust.
Other assets that should probably not be transferred to your trust are incentive stock options, Section 1244 stock and professional corporations. If you unsure whether or not to transfer an asset to your trust, check with your attorney.