Congress created the 403(b) as a nonprofit version of the 401(k) legislation for those employed in nonprofits, like higher education. Typically university and other nonprofit employers would at minimum pay into a tax advantaged investment account owned by the employee. Many also offered matching amounts, like with the for profit 401(k)s. I remember getting a 12% match on my 8% contribution at my (private) university back in the old days!TIAA was at first just about the only game in town; but over time Vanguard and Fidelity made headway and are offered along with TIAA and others in the nonprofit world. TIAA offers (and this is a simplification) two main areas for investment: safer, interest bearing vehicles and real estate, and securities (stocks/bonds). The biggest risk is with the stocks/bonds offerings but also the greatest reward. Many new employees would just allocate 50% to the paper assets and 50% to the stocks/bonds. During my years as a contributor the general Stock/Bond fund (called "CREF" at that time) consisted of an indexed (S&P I think) core and a smaller actively managed piece).
I was employed in higher education almost all of my life and was covered by TIAA-CREF (now, called only TIAA) before I moved to Europe. TIAA and its products are very complex and require a lot of careful thinking before acting. For example, your final payout rate includes different rates on tranches of your TIAA investments over the years, each paying different interest rates on your contributions during those years...higher in the 80s and 90s of course). Plus, of course, mortality credits. As an investor client, you always can see very transparently which of your accumulations pay what interest rates. When you are ready to retire, you can request any number of models of different options available to you. TIAA, like anything that lasts more than a hundred years, has grown its offerings in helpful ways and offers a complexity as a by product.
You have several choices, OP. You can annuitize some or all of your TIAA accumulation for a lifetime annuity (with all the variations on single/two life, guaranteed period, etc.). You can also opt for an annuity with a built in inflation protector (some of the payout is held back and reinvested regularly for a higher future payout). You can opt for an interest only payout, where you do not annuitize but are simply paid the 3% (with potential plus amounts determined each year) interest. Then decide later if you want to annuitize. Finally, if your TIAA accumulation includes the TREA (TIAA Real Estate Account), your payout will take advantage of any growth (or loss) in that asset. So, a lot to consider.
IIRC, you mention that the TIAA traditional annuity accumulation is 20% of your total TIAA and CREF (stock). And, annuitizing that amount alone would cover your retirement needs. So, in some ways this acts as a bond allocation, at present. Just with a likely higher payout because your funds have variable interest rates based on those tranches I mentioned earlier.
Note: TIAA staff do the work advising and then creating the annuity for you. They do not earn commissions. They are salaried employees. That said, they don't always know what they are talking about on the phone, so be wary. Always confirm yourself what they tell you.
To be clear, you CAN withdraw your TIAA as a lump sum, but only over a ten year period (again, it's complex: technically ten, but in actuality nine). So, cashing out can be done but only in slow motion. Slow motion is what TIAA is all about. It moves slowly, and carefully. You cannot do things, as a client, that might negatively affect your fellow clients. So, the cash out is over a decade to blunt the effect on everyone else. It's a deliberate design to ensure stability of their payout capability.
I have been a client since 1984 and have been very happy. They manage hundreds of billions of dollars in assets for some 5 million clients in higher ed, secondary school, hospitals, and other nonprofits. The four credit-rating agencies all give TIAA-CREF their highest possible ratings: A++ from A.M. Best, AAA from Fitch, Aaa from Moody's, and AAA from Standard & Poor's. They were founded 102 years ago by the Andrew Carnegie Foundation as a nonprofit in order to ensure that professors could have comfortable retirements (which were lacking in 1918). They grew in popularity and in AUM over the next 80 years. In 1998 they were forced out of their nontaxable status because for profit investment firms didn't like their untaxed competition and lobbied the federal government. So, in return they asked to be allowed to create a for profit subsidiary to sell mutual funds and immediate annuities retail. That is a completely separate business.
When I retired five years ago I annuitized my TIAA/CREF accounts to provide one reliable income stream (about 25% of my total invested assets). While a fixed annuity mostly, it nonetheless has increased by 1 or 2% in 3 of the 5 years. Also, the TREA portion has added some growth as well. This year might be a loss, however. In any case, my TREA component is only about 10% of the total accumulation that I annuitized.
I am happy to have this backstop and I treat it like a bond asset in my allocation model. This allows me to take on more risk in my after tax stock portfolio. It allows me to sleep at night when the markets are in full volatility mode.
Wow, a long treatise here; but I cannot emphasize more...do your homework and due diligence before acting. The annuity in its various flavors might work for you; the interest only payouts for now, or something else. Study up online...there are a ton of resources online and some good ones from TIAA itself. Most important, I trust the core group of people at MorningStar's community forum on "TIAA". Join up and pose your questions, they will help you out. Some are retired fellow economists, finance professors, etc. and know what they are about. You can trust their advice.
Hope this helps...
-BB