I don't know anyone who enjoys preparing their annual income taxes, so why would anyone want to redo the tax forms they've already filed?

For some people, there could be compelling reasons to do just that.

Let's say you are a South Carolina homeowner who just learned you could claim a large state tax credit for paying outsized homeowner's insurance premiums -- and could have claimed such credits in previous years.

I've talked to several people who didn't know about the Excess Insurance Premium Credit, worth up to $1,250 for people who spend more than 5 percent of their income on homeowner's insurance, until they read about it in my column. One of those people expects to save nearly $1,100 on his S.C. taxes this year.

And that person could have saved a large amount of money last year if he had known about the tax credit at the time.

Remember, a tax credit is much more valuable than a deduction. A tax credit reduces the amount you owe, dollar for dollar, while a deduction reduces your taxable income. So for South Carolina state income taxes, a dollar of tax credit is worth a dollar, while a dollar of tax deduction is worth up to 7 cents.

In a situation where a person might gain thousands of dollars by redoing prior years' tax returns, it would seem worth the trouble to file those amended returns, even if it involves hiring an accountant.

In 2009 -- that's the most up-to-date information available from the S.C. Department of Revenue -- the Excess Insurance Premium Credit was claimed on just 1,261 returns. It seems fair to assume a much larger number of tax filers qualified, considering the cost to insure a home near the coast.

For those who qualify, the credit is subtracted from income tax owed to the state, and unused credits can be carried forward for up to five years. That means claiming the credit one year could reduce your tax bill up to five years later.

On the federal side, the Earned Income Tax Credit and the Retirement Savings Contributions Credit offer substantial benefits for people with low to moderate incomes that are often overlooked. Statistics show that both credits are claimed by far fewer people than likely qualified.

The Earned Income Tax Credit is available primarily to working people with children. Those with no children can qualify but only if they have very low incomes. The credit is refundable, which means you can get the tax credit even if you owe no income tax. Go online to www.irs.gov/eitc for information.

The Retirement Savings Contributions Credit, also called the Savers Credit, is a widely overlooked federal tax credit for people with low to moderate incomes who make contributions to retirement accounts. A single person earning as much as $27,750, and a married couple earning up to $55,500, can qualify for a tax credit worth 10 percent to 50 percent of the amount contributed to retirement accounts for that tax year, up to certain limits. Online, see IRS Tax Topic 610 or Publication 590 for information.

If you missed some big tax breaks, here's what you need to know about filing amended returns:

If you file an amended return, in most cases you'll need to file both state and federal returns because changes to one have an effect on the other. For example, South Carolina income tax returns start with the income claimed on your federal return.

Typically, amended returns can be filed within three years of the original filing date. Federal information is at irs.gov (Tax Topic 308); state information is at sctax.org.

Reach David Slade at 937-5552. On Twitter: @DSladeNews.