If you're not using an individual retirement account, you may be paying more in taxes. More importantly, you might not be saving enough for retirement. The good news is that opening an IRA account is easy, once you've decided on a brokerage.

Below, we'll take a look at what TD Ameritrade and OptionsHouse have to offer do-it-yourself investors by comparing them on the things that matter most for retirement savers.

Commission prices

Making a trade isn't free, but prices are falling closer to zero with each passing day. While fees and commissions aren't everything, it's definitely something to take into consideration. The table below reflects standard commission prices that OptionsHouse and TD Ameritrade charge for online trades.

Brokerage

Stocks and ETFs

Stock Options

Mutual Funds

OptionsHouse

$4.95 per trade

$4.95 + $0.50 per contract

$20.00 per purchase

TD Ameritrade

$6.95 per trade

$6.95 + $0.75 per contract

$49.99 per purchase

Data sources: Company websites.

Notice that the difference for stock, exchange-traded fund (ETF), and options trades adds up to a couple of dollars on the base rate. The biggest difference is in mutual fund pricing. Keep in mind, however, that TD Ameritrade has many mutual funds you can buy for free, which makes its standard commissions more of a guide than a certain price for every single trade.

Mutual funds, ETFs, and commission-free choices

It's becoming more and more common for brokers to carve out certain lists of investments that their clients can buy or sell without paying a commission. Take a look at how these brokers compare on freebies in the table below, but note that quantity isn't everything. Whether or not your broker's list of free funds includes the ones you like to use is most important.

Brokerage

Total Mutual Funds

No-Load, No-Transaction-Fee Funds (NTF)

Commission-Free ETFs

OptionsHouse

More than 12,100

None

5 (O'Shares)

TD Ameritrade

More than 11,800

3,800

101 (iShares, Vanguard)

Data sources: Barron's, company websites, and representatives.

TD Ameritrade is something of a leader in making mutual funds and ETFs free of any transaction-related fees or commissions, offering up nearly 4,000 funds and ETFs that you can buy for free. However, any fund that does not make TD Ameritrade's free list is more expensive to buy through the brokerage than it is to buy through OptionsHouse.

Minimum deposit requirement for IRAs

Some financial services companies require certain minimum deposits to become a customer, but the practice isn't as common in the discount brokerage industry. Neither OptionsHouse nor TD Ameritrade have a minimum deposit requirement, making them no-minimum brokers, fit for an IRA of any size.

A couple rests on beach chairs to watch the sunset.

There's no such thing as starting too small. Small contributions to an IRA over time can really add up. Image source: Getty Images.

Investing in foreign stocks and ADRs

If foreign stocks are an important part of your strategy, you'll need to shop more carefully for a brokerage. Many brokers, TD Ameritrade and OptionsHouse included, allow only their clients to trade foreign stocks that have an American depositary receipt (ADR) on a U.S. exchange. In general, only the largest foreign companies -- think Honda or BP, for example -- have an ADR.

Smaller foreign companies typically are listed only on their home exchanges, so you'd need a broker for international trading to invest in them. In general, trading overseas markets -- and ADRs, at some brokers -- tends to be more expensive than simple domestic stock exchange orders. 

Mobile app reviews

Modern brokerages enable their clients to place trades from anywhere in the world through an app on their mobile phones and tablets. Here's how each broker's users and customers rated their mobile trading apps, as of March 15, 2017.

Brokerage

Apple App Store

Google Play

OptionsHouse

1.6 stars

3.1 stars

TD Ameritrade

3.5 stars

3.5 stars

Data sources: Relevant app stores.

IRA account fees and service charges

IRA fees are common, but some are avoidable. Two common fees in the industry are maintenance fees -- just for having an IRA -- and inactivity fees -- for not making enough trades each month or year.

Luckily, neither TD Ameritrade nor OptionsHouse charge either kind of fee, but it's something to pay attention to if you comparison shop other discount brokerages.

OptionsHouse vs. TD Ameritrade for IRAs

The truth is, how you invest has a huge impact on which brokerage is best for you. In this case, OptionsHouse has lower standard commission prices for stocks, ETFs, mutual funds, and options. On the other hand, TD Ameritrade may win over fund investors due to the fact it offers nearly 4,000 mutual funds and ETFs that its clients can buy and sell commission free. 

Ultimately, it's all about how a broker's offerings align with your portfolio. To be clear, The Motley Fool does not endorse any particular brokerage, but we can help you find one that's a good fit for you. Visit Fool.com's IRA Center to compare several leading discount brokers on one page.

Jordan Wathen has no position in any stocks mentioned. The Motley Fool recommends TD Ameritrade. The Motley Fool has a disclosure policy.