If you’re doing your own taxes, think about this rule of thumb: The more complicated your tax return, the more you need software to help you prepare it. Both Intuit’s TurboTax and H&R Block At Home will guide you through the tax prep process for any financial situation while informing you about tax breaks that you might not be aware of. And as in previous years, TurboTax does a better job of it than H&R Block At Home.

TurboTax is a more user-friendlier interface to a decidedly user-unfriendly tax code, providing superior help, better navigation of the software, and great error checking. H&R Block At Home will do the job and offers options to pay for expert advice should you run into trouble. But it is more difficult to use, and revealed some rough edges, including some incomplete answers to tax questions and clunky error checking.

In order to evaluate a large number of tax situations, I reviewed TurboTax Home and Business and H&R Block at Home Premium, versions of the desktop software that can handle investments, rental property, and self-employment. Less expensive versions are also available for simpler tax situations.

Both companies also offer on-line versions that have a similar (though not identical) look and feel as the software versions. The Web versions, however, are not as responsive as the desktop software versions, and are a little more frustrating to work with. And having your tax data file on your Mac rather than in a cloud means you don’t have to worry if the company will be around if you need access to your data in a few years.

Import data

TurboTax and H&R Block At Home have similar import capabilities. Both packages start by asking you if you want to import data from previous year’s tax files. This will save you the hassle of typing the names of banks and sources of income, and will import carry-overs from last year, such as capital losses, credits, and depreciation figures. You’ll also import the names of businesses you operated last year and the associated codes and IDs. One deficiency with H&R Block At Home is that it did not import 1099-MISC data from the previous year’s data file

H&R Block At Home can import TurboTax files, though I found that I had the same missing 1099-MISC data problem. TurboTax can't import the native format of H&R Block's data, but it can import returns that were saved as PDFs.

Both applications also can download and import current tax info, including W-2 forms from a limited number of employers, and several types of forms from financial institutions, such as the 1099-INT (interest income), 1099-DIV (dividends), and 1099-B (stocks and capital gains).

Both programs can also import data from Quicken. H&R Block At Home can also import Microsoft Money (a Windows-only application), and programs that supports the Tax Exchange Format (TXF). TurboTax imports data from PDF files generated by H&R Block and TaxAct, a Windows application.

Both applications can import data from their respective companies’ free Websites. H&R Block At Home imports data from Deduction Pro, which helps you determine the tax-deductible value of items you donate to charity. TurboTax imports from Intuit’s ItsDeductable, which is equivalent to H&R Block’s Deduction Pro, as well as from Mint.com, a site for organizing your finances.

The interview

Both programs collect information and data from you through an interview—a series of screens that ask you questions about your tax situation and provide explanations of the technical terms. Theoretically, you could start at the beginning of the interview and to answer each question as they come through all the sections. But, you aren’t likely to use the software this way. You’ll skip sections that don’t find information you may not have at hand, you’ll go back and change answers. TurboTax and H&R Block enable this in several ways. The interview is organized into sections about income, deductions, and other items, to which you can navigate using tabs. There are also summary pages near the beginning of sections that enable you to go to subsections for specific types of deductions, income, and other items. And both let you search for topics in the interview.

TurboTax has a more fluid approach to the interview with some special navigation features that enable you to jump around fairly effortlessly. TurboTax lets you bookmark screens where you left off in order get back to exactly where you were. The bookmarks are called “flags,” which you can give your own names and assign an explanatory note. You can create an iCal reminder for a flag to set deadlines for yourself for collecting information. This is a feature you will likely use frequently.

H&R Block at Home does not have a bookmarking feature, which makes getting back to where you were a bit of a chore. There is no way to get to a specific screen; you can only click to the beginning of a section, and then click through screens until you find the one you need—if you can remember which one it was.

Another great TurboTax feature is Notifications, a collapsible section that sits under the Flags section in the left column. Notifications remind you if you’ve skipped information, such as an Employer ID Number in a 1099-MISC. Each Notification presents two buttons: a Flag button turns it into a flag, allowing you to enter a note. A Fix button takes you to exactly to the page where you can enter the information.

H&R At Home navigation has improved in one respect. Previously, if you jumped to a different section, the Back button took you to the previous screen in the section you jumped to—not to where you just were. In this year’s version, the Back button turns into a Previous Screen button that takes you the screen you just left. The problem is that it works only once. TurboTax’s Back button works like that of a Web browser, taking you back to the screens in the reverse order you visited them, regardless of the section in which the screens are located.

Both programs let you easily switch between the interview screens and the relevant IRS form or worksheet and enter or edit data there. This is useful if you are familiar with the IRS forms.

Navigate the tax code

The interview screens hold your hand, providing links to explanations of what they are asking. But you will still need help with the ever-changing tax code. Here again, TurboTax comes out ahead.

Both products provide the official IRS publications, and present more digestible tax information that is relevant to the particular interview screen you’re on. They also both let you ask a tax question that returns a set of answers from an online database.

TurboTax’s Live Community is superior to H&R Block’s Ask a Tax Question. H&R Block launches your Web browser to present a list of relevant questions and answers. TurboTax’s Live Community is integrated into the software, so you don’t have to leave your interview page.

But more interesting is that TurboTax’s Live Community is a kind of a social networking area. When you click on a question, you’ll see responses from multiple users, as you can in an online forum. You can rate answers, click to send a thank you to the answerer, and click a button to watch the topic, which sends you an e-mail when someone else responds. And, Facebook and Twitter buttons let you share an answer that you found particularly interesting.

If the answer to your question isn’t in the database, it will be posted in Live Community for someone else to answer. You can also submit answers to others’ question, and gain points. As incentive, the users who answer the most questions are rewarded with a listing in a leaderboard. However, I didn’t find any questions for which TurboTax Live Community didn’t return an answer. I did in H&R Block. For example, in TurboTax, a question about deducting a tractor brought up items related to farming. H&R Block’s returns were completely irrelevant and unrelated.

Even worse, H&R Block’s Ask a Tax Question section provided incorrect answers to the question: “Can I deduct medical premiums?” The answer was always “no,” which is true for most people—but not all. The healthcare reform that Congress passed gives certain self-employed people an income adjustment for premiums. Although the H&R At Home interview pages do include this, if you read that the help answer was “no,” you might skip the section of the interview and miss this opportunity to save money. TurboTax’s Live Community provided the correct answer to this question, multiple times.

Somewhat confusingly, H&R Block also has a second site, called Get It Right: Community, where you can ask questions. This yielded better answers than the Web-based database that the software sends you to. However, we could find no direct link from the software to the Get It Right site.

Both programs let you write a direct question to a tax expert and speak to them by telephone. H&R Block gets the nod here, giving you a free session. For $30, TurboTax lets you ask a question tax expert, who will call you within 60 minutes. You can then talk for up to 20 minutes.

Cleaning up your return

It’s best to complete your federal information before starting the section on your state tax return. That’s because both applications will copy any applicable information into the state section before asking you additional questions. After you enter all your data, you can have the software check the return for errors and missing information. The two applications are comparable here.

After error checking, both programs can produce summary reports. TurboTax makes suggestions for deductions you may have missed. It also creates charts comparing this year’s and last year’s income, withholdings, deductions, and taxes paid, with related recommendations. It also calculates the likelihood of an audit based on best practices for tax returns.

H&R Block At Home provides some similar statistics, as well as suggestions for retirement planning. The most useful feature here is an option to calculate an estimated 2011 tax and withholding, which is useful if you file quarterly payments.

You can file your returns electronically right from the applications or print out your returns. H&R Block and Intuit both offer free support from a tax professional in the unlikely event that the IRS audits your return.

Macworld’s buying advice

Both H&R Block At Home and TurboTax will prepare a tax return even for the most complex situation, and provide instruction along the way to help you get the lowest tax bill. But TurboTax is easier to use, which means you’ll get your taxes done faster. TurboTax provides easier access to the tax help, and in some cases, more accurate answers to tax questions than does H&R Block At Home. TurboTax is a bit more expensive than H&R Block At Home, but it’s certainly worth the extra money.

[John Rizzo is the publisher of MacWindows.com and the author of Snow Leopard Server for Dummies (Wiley, 2009).]