As the adage goes, there's an app for almost everything, so with tax season in full swing it's not surprising that there are apps for filing taxes.

Both H&R Block and TurboTax have apps that enable users to file taxes with their Apple or Android smartphones.

But how good are they? Can users file their federal taxes with just a few taps on 4-inch screens?

That's what I set off to find out, and the answer for most people will probably be no.

The H&R Block 1040EZ 2012 app, otherwise known as H&R Block at Home, and the TurboTax SnapTax app let users fill out a tax return and electronically send it to the Internal Revenue Service.

But unless their tax returns are simple, users will end up having to complete them on a tablet or computer.

Of the two, I found only TurboTax's SnapTax helpful. With the app I was able to input my W-2 information by simply taking a photo of the form. The app provided a simple tutorial on how to do so.

Although I had to manually enter information for a field the photo feature failed to scan, the app easily saved me at least 10 minutes.

But when I had other information to input, such as a 1099-MISC, the app redirected me to the company's online software to complete the return. I recommend the free app only if you are filing a 1040EZ.

H&R Block at Home's smartphone app didn't offer me any help. One of the first pages users encounter is "Qualifying Questions," on which users check off any situation that applies to them. Among the options are whether users have any dependents, own a home or had income that wasn't from a W-2, interest or unemployment. If a user checks any of the 11 options, the app says it doesn't support the tax situation and encourages the user to go to the online site.

So for now, smartphone apps have a ways to go before they can replace a computer or a tax preparer, though apps for tablets seem to be closing the gap.

H&R Block and TurboTax each have apps for the iPad that use the same software as their online counterparts and thus can be used interchangeably, which I did. I tried both apps and found them helpful, with simple language and a clean interface.

You can use both apps free of charge, but depending on the complexity of your filing, you'll probably have to make an in-app purchase to upgrade and use the software's more capable versions. But they don't charge you for the upgrade until you file your taxes electronically or print them.

This allowed me to compare the services and see which version promised me the bigger refund. For my federal returns, the iPad's TurboTax app offered me about $300 more in refunds than H&R Block at Home.

But for good measure, I went to an H&R Block office to see whether it's worth having a tax preparer help me, or whether using an iPad app or online software was enough. This is a service TurboTax doesn't offer, but in its defense, it has a vast library of frequently asked questions and a section on its website where users can post questions and receive help from others. TurboTax also lets you live chat or speak on the phone with one of its professionals. TurboTax won't go line by line with users on their files, but users can ask an unlimited number of questions free of charge.

Regardless, I found meeting with a tax preparer helpful. Not only was it more reassuring than staring at my iPad, but the preparer also caught a few mistakes I had made. In the end, my federal tax refund was $200 more than what TurboTax had promised. I paid $150 for the service. By comparison, it would have cost me about $67 to file my federal and California taxes with TurboTax for the iPad.

My advice? Because all these apps are free to try and you pay only if you file, use them and go with the one that will save you the most money and give you peace of mind.