Best tax software of 2021: File fast and accurately, plus get your maximum refund

Tax season is upon us, and for many Americans that means signing up for an online tax software.

The IRS started accepting and processing tax returns on February 12, so you can begin filing your state and federal returns as soon as you have all your documents. After all, the sooner you file, the quicker you’ll receive any refund you’re owed, assuming there are no issues with your return. The federal tax deadline is Thursday, April 15, 2021.

Doing your taxes isn’t a fun task, but you can make the process faster by filing your tax return using a tax software program. Services like TurboTax and H&R Block walk users through the process so you can maximize deductions and increase your refund. Many of the best services offer both free and paid plans that allow you to select the option that best suits your needs — whether this is the first time you've needed to file or you've been paying taxes for years.

CNBC Select reviewed 12 tax filing software programs, evaluating them on a range of features, including cost, user experience, expert tax assistance and Better Business Bureau rating. (Read more about our methodology below.)

Here are the best tax filing software programs.

• Best overall tax software: TurboTax
• Runner-up: H&R Block
• Best free tax software: Credit Karma Tax
• Best affordable tax software: TaxSlayer
• Best for accuracy guarantee: TaxAct

FAQs

• When are taxes due?
• What happens if I miss the tax deadline?
• How much does it cost to file taxes?
• Simple tax return vs. complex tax return

Taxes are due on Thursday, April 15, 2021. While the IRS extended the deadline to file taxes last year to July 15, 2020 due to the coronavirus pandemic, there are currently no plans to repeat the extension this year.

If you miss the April 15 deadline, you still need to file your taxes and should do so as soon as possible. You'll incur a penalty if you file late and owe taxes, which only gets pricier the longer you wait. You won't incur a penalty if you don't owe and instead have a tax refund coming.

Many tax software programs have a free version, but you'll be charged a fee if you upgrade to a paid plan. The tax programs we reviewed either have no cost for the free plans, or charge as low as $11.05 for federal filing plus $4.95 per state. However, the costs can add up fast with the more complex deluxe, premium and self-employed plans — the most expensive is $170 for federal, plus $50 per state. If you want to add live tax support, the surcharge can be $35 to $100, plus state fees.

We found that the most affordable service is TaxSlayer. The Classic plan supports all tax situations and currently costs $11.05 for federal and $32 per state (when you take 35% off with the code SLAYIT35).

A simple tax return is the most basic type of tax return you can file, and many tax software programs let you file this return for free. A simple return generally includes W-2 income, limited interest and dividend income, standard deductions and unemployment income.

Some free plans also include the earned income tax credit (TurboTax, H&R Block, Credit Karma and TaxAct), child tax credits (TurboTax, H&R Block, Credit Karma and TaxAct) and student loan/education deductions (H&R Block, Credit Karma, TaxAct and TaxSlayer).

If your finances are more complicated and you don't qualify for a simple tax return, you'll need to file a complex tax return, and most tax software programs will charge you fees to file. Complex tax situations typically include anyone with freelance income (1099 tax forms), small business owners and landlords, as well as anyone with earnings from investments and stock sales.

The tax program you use will notify you if you can't file a free simple tax return and instead need to upgrade and pay to file a more complex return. And even if you can file a simple tax return, you may want to pay for the next-tier plan to benefit from more deductions.

To determine which tax software offers the best way to file your taxes online, CNBC Select analyzed 12 programs. We compared each program on a range of features, including:

• Cost
• User experience
• Expert tax assistance
• Accuracy and maximum refund guarantee
• Better Business Bureau (BBB) rating
• Customer reviews, when available

Cost was one of the most important factors. While many of these services offer free versions, many people have complicated finances that require them to pay to file their taxes. We evaluated the price per plan and weighed the features you receive, like the ability to maximize deductions and credits. The more bang for your buck, the higher a service ranked.

Whether you're new to filing taxes or a seasoned pro, user experience is crucial to filling out and submitting your return quickly and with little frustration. The services we chose had to be relatively user friendly.

The ability to speak with a tax expert or support representative was a big plus. Four out of five of the best tax software offered some form of support.

And if a service supported consumers with a generous accuracy and maximum refund guarantee, it was ranked higher.

We also considered the Better Business Bureau rating associated with the software. BBB ratings help determine whether a business is operating responsibly and if it helps to resolve customer complaints in a timely manner. Customer reviews were also taken into consideration.

After reviewing the above features, we sorted our recommendations by best for overall tax filing, runner-up, free tax software, most affordable and best accuracy guarantee.

The federal and state filing fees for the software programs mentioned above are subject to change without notice. Many programs don't charge you until you file, so there's a chance the fees can change from the time you start your return until you submit it.