If you rollover you will never be able to do Backdoor Roth IRAs.
Incorrect. Frankly, a lot of the advice in this thread is nonsense. To do a Backdoor Roth IRA later (which is beyond the scope of SuperHiro's question), all of your IRAs at that time will need to be in or converted to a Roth account. You can invest in a 401k/403b during residency, roll (and convert if it was pre-tax) that into a Roth IRA later, and still be eligible for later backdoor Roth IRAs. See:
http://www.bogleheads.org/wiki/Backdoor_Roth_IRA
does anyone have any more advise on this subject? I am still confused about the difference between a TSA vs IRA, vs 401k. Is there any disadvantage to investing now? How do I know why my retirement tax bracket will be? What is considered a good employer investment return?
IRA = Individual Retirement Account. This can be pre-tax or post-tax. The difference is that you either pay taxes now (Roth IRA), and when you take it out as a qualified distribution (i.e. when you retire and certain other situations) it is federal tax free. Or you can pay taxes later (Traditional IRA), at which point it will be taxed as income. The contribution limit is $5,500 this year (assuming single income up to $112k/married $178k).
Tax brackets are whatever they are now. Everyone likes to sit around and argue about what the future will hold. Nobody knows what the future holds, but everyone like to say X and Y WILL happen, which is nonsense. When you plan, plan based on what's happening now. That is, your top tax bracket on your resident salary is almost certainly 25% (
http://www.tax-brackets.org/federaltaxtable). What bracket do you plan to be in when you retire? 100k/year or 28%? If so, it benefits you to pay the tax now (i.e. post-tax (Roth) IRA/403b) because it is a lower tax rate (25%) than it would be later (28%). You can speculate that taxes will go up in the future, if so, it benefits you to pay the tax now. You can also speculate the government will do things like find ways to tax Roth IRA earnings, in which case it benefits you to pay the tax later. This is all speculation. If you want to hedge, you can actually do a traditional IRA and a Roth 403b or some other mix or pre and post-tax.
If you want to start an IRA, great. You just open an IRA account. If you're doing it as a Roth (post-tax), you take some of your income, put it in the account, buy some investment, and you're done. The company tells the IRS about it. You've already paid the taxes on it. Everyone is good. Great, now how do you decide where to put that money? That's a matter of extreme debate. It depends on a lot of different things. At our level, I like the "core 4 80/20" portfolio here
http://www.bogleheads.org/wiki/Lazy_portfolio. But you can go to that site and other places and find other portfolio options. I love Vanguard for a lot of reasons. Option #2 would be Schwab, which also has a great banking option associated with it. So let's say you open an account with Vanguard, transfer in $5500, and buy the funds listed on that page in those percentages (sign up for all electronic delivery of all documents and pay no fees at all ever). You transfer more money in every year of residency. Bingo blammo eventually you retire. Haha, sort of. You'll want to convert your portfolio to a less risky one as you get closer to retirement, but eventually you'll want to start reading more on your own or get a financial advisor. Financial advisors are mostly scam artists, but that's another discussion for another day.
TSA = 401k/403b generally. 401k = for profit company, 403b = non-profit company, and that's all you really need to know because for you, the saver, these are essentially the same thing. These are maybe offered by your employer. My residency program does not offer a 403b, so this is moot for me. The question becomes, does your program offer a 403b, and if so, do they "match". Matching is when they give some of their own money in addition to what you contribute. If they do, this is essentially free money and is typically in your best interest. The only problem with the matching may be if you are vested. That is, your employer only matches your contributions if you are with them for so long (typically some number of years, often more than your residency length). You have to look into the details of your TSA for more information. If they don't match at all, the TSA can still be a good tax sheltered place to put retirement investments once your IRA is maxed out. The disadvantage to a TSA over a well invested IRA is that there are often fees and/or lousy funds associated with these TSAs, so you have to be careful what they are doing with your money, and allocate your funds as you see fit. When evaluating your options within a TSA, pay special attention to any fees, and check out the expense ratios of the funds and their past performance. Try to fit all of your investments into your overall portfolio that I showed earlier, preferably by investing in Vanguard or similar index/low-cost funds. The TSA should have something like these options, but if not you'll have to play around with it a bit to get it to fit a reasonable mix of the total stock market, bonds, and international (with optional REIT or others). Just avoid anything called an annuity or a fixed income option. They are often the default options for these TSAs, and they are rip offs that benefit the company running the TSA only.
When you leave your residency/fellowship you can "rollover" that TSA into your IRA. Make sure you do this as soon as you can after you finish with that program. If both your IRA and TSA are post-tax, they just get combined into your IRA for you to invest however you see fit. The TSA/former employer is then completely out of the picture. You can "convert" pre-tax to post-tax investments at a later date by paying the taxes on a Traditional TSA/IRA then combining it into a Roth IRA.
The only disadvantage to investing now is that you may have debt that accrues more interest than you earn on the investments. For example, if you have student loan interest at 6.8% and you invest money, you are assuming your investment money will make at least 6.8% if you want to break even. Reasonable portfolio gains are on the order of 5-6%/year, so my general advice is always to pay down debts higher than say 5% before investing for retirement.
Note there are some other parts of a complete financial assessment that get very personal and may or may not apply to you (family situation, insurance products, etc) that I'm not commenting on. A lot of people buy life insurance, disability insurance, and overlapping coverages (i.e. things that are covered by multiple products one of which may be residency/fellowship provided without their realizing it...) that they simply don't need. People who sell these products to you make money by selling them, and hence want to convince you of their value. People who buy these products want to convince themselves of why they bought them, and hence want to convince you of their value. So buyer beware.
TL;DR HOLY CRAP WTF NEURONIX
Assuming you do not have debt or you only have low interest debt, you are single, and you are earning resident/fellow salary, Cabby's post (#12) is still good advice. I would say in order of investment priority for a resident or fellow:
1) Matched post-tax (Roth) 401k/403b (IF AVAILABLE, see details of your plan)
2) Post-tax (Roth) IRA
3) Unmatched post-tax (Roth) 401k/403b (if available)
4) Taxable account
If you have debt or a family, things are more complicated. Generally pay the debt off first. If you have a family, especially children, learn a lot more (particularly read up on 529 college savings plans and life insurance) or get a *fee-only* financial advisor. Fee only advisors do not make money based on what products they sell you, only based on what you pay them. Paying a good advisor a fee for their advice is far less costly than free advice that steers you to costly and/or unnecessary products.
Final note:
The taxable investing above gets into a whole different ball of wax. I'll assume you don't have that much to invest (IRA limit $5500, TSA limit is $17500 for grand total of $23000/year of post-tax investment goodness, which is probably >50% of your yearly post-tax income). Once you become an attending and have more money, things get (much) more complicated. Hopefully you will have other ways of tax sheltering your money at that point that go beyond the scope of one SDN post. See the awesome whitecoatinvestor blog for more information on this and other topics:
http://whitecoatinvestor.com/new-to-the-blog-start-here/ . Also, the Bogleheads forums and wiki
http://www.bogleheads.org/wiki/Main_Page has a wealth of sound investment information.