Every year brings new twists in tax law. Three of this year’s twists call for special consideration by people who own or run businesses.

1. Estate tax
Until Congress decides otherwise, the estate tax will disappear in 2010 and then revert in 2011 to the old rate of 55% for estates worth more than $1 million.

There are any number of moves Congress could make in 2010, including passing an estate tax bill and making it retroactive. Because of possibilities like that, financial planners and accountants are pulling their hair out. Most expect that the estate tax will be reinstated this year, although no one’s sure what the rate will be or if Congress will throw in some new stipulations.

What to consider in your estate planning: Check with your accountant or tax adviser to determine whether it might be better to gift or loan money to heirs, rather than leaving the cash in an estate.

2. Gift tax exclusion
In 2009, the IRS allowed people to give up to $13,000 a year to anyone, tax-free, and separate from the $1 million lifetime exemption on gifts.

Do the math to determine the advantages: If you have an estate subject to a 45% estate tax, each $13,000 gift will save at least $5,520 in estate tax. Consider an example  in the New York Times: A married couple with a $10 million estate gives $13,000 a year each to six people for a 10 years. At the end of that time, they will have given $1.56 million tax-free — money that would have been hit with $702,000 in taxes if left as part of their estate.

3. Roth conversion
Congress changed a lot of the rules regarding Roth IRAs and conversion of IRA money into a Roth. The main change in the conversion laws removed the $100,000-a-year income limit for people who want to convert to a Roth. There are other advantages, too. For the full range, go here.