Can an IRA be taxed?
The Motley Fool article is correct that if you earn UBTI over $1000, you will need to pay the tax, even if held in an IRA.   C-corps won't generate UBTI, so you're fine with those.  For non-C-corps, the most common are REITs, MLPs, and BDCs.   REITs  These typically invest in either real estate property or mortgages.  The ones that invest in mortgages are sometimes notated: mREITs, and can occasionally generate UBTI.  Tip: Don't let this stop you from investing in REITs in your IRA.  REITs can be a great source of income and are best held in an IRA since the income will be tax free vs. your ordinary income tax bracket if held in a taxable account.  Some examples of mREITs would be NLY, CIM, AGNC.  Some property REITs would be: O, SNR, OHI, EQR. https://seekingalpha.com/article/1257351-tax-bomb-mortgage-reits-triggering-ubit MLPs Master Limited Partnerships are also pass-through entities, like REITs, but have the additional complication that most issue K-1 forms at tax time.  K-1s can be very complex when the MLP owns assets across state boundaries, which is why I actually PREFER to hold MLPs in my IRA (against the advice of M. Fool) since I won't have to deal with the tax complications of filing the K-1, just as long as my MLPs don't generate over $1000 of UBTI. https://seekingalpha.com/article/4057891-mlps-kminus-1s-ubti-oh BDCs Business Development Companies like REITs and MLPs are also pass-through entities in that the income they give you will be taxed at your ordinary income bracket if held in a taxable account.  Examples of BDCs include: MAIN, MCC, ARCC.  You'd need to consult their 10-K to determine if there is a risk of UBTI. Tip:  MLPs, BDCs, and especially REITs can all be very valuable sources of income and from my experience, UBTI is rare so don't let that scare you away if you otherwise like the investment.
You have many options, and there is no one-size-fits-all recommendation. You can contribute to your IRA in addition to your 401(k), but because you have that 401(k), it is not tax-deductable. So there is little advantage in putting money in the IRA compared to saving it in a personal investment account, where you keep full control over it. It does, however, open the option to do a backdoor-rollover from that IRA to a Roth IRA, which is a good idea to have; you will not pay any taxes if you do that conversion, if the money in the IRA was not tax deducted (which it isn't as you have the 401(k)). You can also contribute to a Roth IRA directly, if you are under the income limits for that (193k$ for married, I think, not sure for single). If this is the case, you don't need to take the detour through the IRA with the backdoor-rollover. Main advantage for Roth is that gains are tax free. There are many other answers here that give details on where to save if you have more money to save. In a nutshell, In between is 'pay off all high-interest debt', I think right after 1. - if you have any. 'High-Interest' means anything that costs more interest than you can expect when investing. It sounds like you're comparing (1) the backdoor Roth IRA and (2) the mega backdoor Roth. Although the names are similar they are considerably different, and not mutually exclusive. The goal of the backdoor Roth IRA is to contribute to a Roth IRA even if you are over the income limits. This is accomplished by contributing to a non-deductible Traditional IRA and then converting to Roth. Both of these steps have no income limit (unlike a direct Roth IRA contribution, which does), and only the earnings (which should be minimal) will be taxed. More info here (mirror). The goal of the mega backdoor Roth is to get a lot of money into Roth accounts through salary deferral. This is accomplished by making non-Roth after-tax contributions to your 401(k) after exhausting the $18,000 limit (in 2017) for pre-tax + Roth employee contributions. The after-tax contributions (potentially up to $36,000 for 2017) can be rolled over to the Roth 401(k) or to a Roth IRA, while the earnings can be rolled over to the pre-tax 401(k) or a Traditional IRA, or taxed like regular income and converted to Roth along with the contributions. More info here (mirror). "I am failing to see why would a person get an IRA, instead of just putting the same amount of money into a mutual fund (like Vanguard) or something like that. Well, this isn't a meaningful distinction. The mutual fund may or may not be in an IRA. Similarly, the mutual fund may or may not be in a 401(k), however. So I'm going to treat your question as if it's ""why would a person get a mutual fund (like Vanguard) or something like that in an IRA, instead of just putting the same amount of money into the same mutual fund in a 401(k)."" Same mutual fund, same amount of money, narrowing your question to the difference between the two types of accounts, as stated in your question's title. Others have answered that to the extent that you really have no choice other than ""pick which type of account to use for a given bundle of money"", other than nobody having mentioned the employer match. Even if there were no other difference at all in tax treatment, it's pretty typical that 401(k) contributions will be matched by free money from the employer. No IRA can compete with that. But, that's not the only choice either: Many of us contribute to both the 401(k) and the IRA. Why? Because we can. I'm not suggesting that just-anybody can, but, if you max out the employer matching in the 401(k), or if you max out the tax-advantaged contribution limit in the 401(k), and you still have more money that you want to save in a tax-advantaged retirement account this year, you can do so. The IRA is available, it's not ""instead-of"" the 401(k)." "Yes, you can withdraw the excess contribution (or actually any amount you contributed for 2015, not necessarily an excess), plus earnings from that withdrawn contribution, by April 15, and not incur a penalty for the excess contribution. It would count as if you did not contribute that amount at all. The earnings would be taxed as regular income, and the earnings may incur a penalty. Yes, you can ""recharacterize"" (all or part of) your Roth IRA contribution as a Traditional IRA contribution (or vice versa) by April 15. Recharacterization means you pretend the contribution was originally made as a Traditional IRA contribution, and did not involve Roth IRA at all. (""Conversion"" is something very different and can only go from Traditional to Roth, not the other way around.) You are likely not eligible to deduct that Traditional IRA contribution, so you will have to report it as a non-deductible Traditional IRA contribution on a 2015 Form 8606 Part 1. Note that after you've recharacterized it as a Traditional IRA contribution, you can also then ""convert"" that Traditional IRA money to a Roth IRA if you want, achieving the same state as what you have now. Contributing to a Traditional IRA and then converting to a Roth IRA is called a ""backdoor Roth IRA contribution""; if you don't have any existing pre-tax money in Traditional IRA or other IRAs, then this achieves the same as a regular Roth IRA contribution except with no income limits. When you convert, the earnings you have made since contributing will be taxed as income. If you had done the backdoor originally to begin with (convert right after contributing), you would have had no earnings in between and no tax to pay, but since if you do the conversion now you have waited so long, you are disadvantaged by having to pay tax on the earnings in between. If you convert, you will have to fill out Form 8606 Part 2 for the year you convert (2016)." "Taxes are triggered when you sell the individual stock.      The IRS doesn't care which of your accounts the money is in.  They view all your bank and brokerage accounts as if they are one big account mashed together.   That kind of lumping is standard accounting practice for businesses. P/L, balance sheets, cash flow statements etc. will clump cash accounts as ""cash"".  Taxes are also triggered when they pay you a dividend.  That's why ETFs are preferable to mutual funds; ETFs automatically fold the dividends back into the ETF's value, so it doesn't cause a taxable event.  Less paperwork.  None of the above applies to retirement accounts.  They are special.  You don't report activity inside retirement accounts, because it would be very hard for regular folk to do that reporting, so that would discourage them from taking IRAs.   Taxes are paid at withdrawal time (or in Roth's, never.)" In the same way that you are taxed on the actual amount of money you convert from the Traditional IRA to the Roth IRA -- rather than on the amount of money that you initially contributed to your 401(k) or on the amount of money that you rolled over to your Traditional IRA -- that converted amount becomes the contributions to your Roth. So (3) is the correct answer. It doesn't matter how you accumulated the money in the first place; as long as the IRS has had the opportunity to dig their claws into it, it counts as a contribution to your Roth. You can contribute to a Traditional IRA instead of a Roth.  The main difference is a contribution to a Roth is made with after tax money but at retirement you can withdraw the money tax free.  With a Traditional IRA your contribution is tax-deductible but at retirement the withdrawal is not tax free.  This is why most people prefer a Roth if they can contribute. You can also contribute to your work's 401k plan assuming they have one.  And you can always save for retirement in a regular account. If you are inside of a ROTH IRA you are not getting taxed on any gain.  Dividends, distributions, interest payment, or capital gains are never taxed.  This, of course, assumes you wait until age 59.5 to do ROTH withdrawals on your gains.