That's correct, muni income is included in the IRMAA calculation.
However, if you get the same net income (after taxes) from a taxable fund and a muni fund, the muni fund looks better from an IRMAA perspective.
For example, and to simplify arithmetic, suppose you're in a 25% tax bracket. A taxable bond fund yielding 4% returns the same amount after-tax as a muni bond fund yielding 3%.
$100 invested in the taxable fund generates $4 of income (gross), while generating just $3 of income in the muni fund. The latter is better in terms of IRMAA.
Even in a 22% bracket, it might be worth taking the $3 tax-free from the muni fund instead of going for $3.12 after- tax return from the taxable fund. You give up a small amount (12¢) of net (after-tax) income with the muni fund but reduce gross income by much more ($1).
That could make the difference between owing IRMAA and staying below its threshold.

Getting pushed into a higher tax bracket itself (without other effects like triggering IRMAA) is often not a good enough reason to use munis instead of taxable bonds.
Say you're at the top of the 12% tax bracket. By assumption any extra taxable dollars will be taxed at 22% and there are no other effects.
As tarheel observed, with current yields one would be better off investing in a taxable fund and getting taxed at 22% than investing in a muni fund. Even if those extra taxable dollars are what's bumping you into the higher 22% bracket.
Likely getting pushed into the 24% bracket is also not enough to make munis attractive today. The 32% bracket would be a different story.
For example, comparing sma3's VWLTX (SEC yield 3.84%) with VWESX (SEC yield 5.25%), the latter yields 3.99% after tax @ 24%. Taxable bonds still "win" (disregarding other concerns like IRMAA).

Munis are more suited for taxable bond funds. "

Sorry, rough night last night. This should read, "Munis are more suited for taxable accounts."

The Week in Charts (08/30/23)
A tour of the markets covering the most important charts & themes, including...
00:00 Intro
00:12 The Purchasing Power Decline (Housing)
03:51 A Dearth of Supply (Housing)
8:55 Disney's Drawdown
11:42 Prepared to Hike Again (Fed)
14:46 A New Computing Era ($NVDA)
18:58 Lower Used Car Prices (Tesla)
22:09 Long Cycles (US Domination)
24:47 The Other Side of Mania (AMC/Meme Stocks)
28:20 The Rental Gap (Suburban versus Urban Rent Growth)
30:58 8 Billion Reasons Thomas Malthus Was Wrong
Video
Blog

From that article:

His study of market history taught him, he said, that long bull markets have four stages: reluctance, consolidation, grudging acceptance and exuberance. This last period is marked by fearless behavior, the entry into the market of unskilled day traders and, ominously, the likelihood of a coming crash.
This led Mr. Birinyi to the paradoxical conclusion that gloomy commentary by market watchers was actually encouraging — before the exuberance stage had taken hold — whereas sunny market reports signified danger.
“So you won’t think the market is going down till everybody thinks it’s going up,” Mr. Rukeyser remarked to Mr. Birinyi on an episode of “Wall Street Week” in 1996.
“Exactly right,” Mr. Birinyi said.

The fund continues to hold a significant investment in bank loans, 11.2%, 7.9% in Treasury Notes, 9.4% in corporate bonds and 7.9% in a money market fund.

NYT article but should be readable by all.
ARTICLE

Stable-Value (SV) Rates, 9/1/23
TIAA Traditional Annuity (Accumulation) Rates
No changes.
Restricted RC 6.75%, RA 6.50%
Flexible RCP 6.00%, SRA 5.75%, Newer IRAs 5.20%
TSP G Fund hasn't updated yet (previous monthly rate was 4.125%).
Edit/Add, 9/2/23. September rate is 4.25%.
Options outside of workplace retirement plans include m-mkt funds, bank m-mkt accounts (FDIC insured), T-Bills, short-term brokered CDs.
#401k #403b #StableValue #TIAA #TSP
https://ybbpersonalfinance.proboards.com/post/1161/thread

Munis including junk munis have been a major disappointment to date in 2023. Without getting into a bunch of technical or fundamental jargon or research, I would simply say so goes the 10 year so goes munis. It has pretty much always been that way.

The generally low IG muni yields with my lower marginal tax rate is why for several years, my only muni investments have been in high yield, and only when they're good buys with a fresh spot of momentum. (And after a good run slows/stops, it's good-bye.)
Thanks for the clarification of your situation, @lynnbolin2021. Of course all of us have individual situations that can make any specific investment a go or no-go.

Due to Labor Day holiday, Monday:
13-wk & 26-wk Auctions will be on Tuesday, 9/5/23.
52-wk Auction will be on Tuesday, 9/5/23 (as typical).
42-day Auction is a CMB, so it isn't on the regular Treasury Auction Schedule. Some brokers may not offer them.
But Settlement dates for these will still be Thursday, 9/7/23.
Orders placed from Thursday afternoon to early Tuesday will be covered by maturing T-Bills on 9/7/23.
Treasury Announcement (note that brokers may have earlier order closing times than Treasury),
https://treasurydirect.gov/instit/annceresult/press/preanre/2023/SPL_20230831_1.pdf

@lynnbolin2021
All depends on what interest rates do which depends on hard or soft landing or "no landing". Long term muni funds like VWLTX are down 3% or so this year. They pay about the same so if interest rates don't go up you may be whole in a while.
Given the various state tax rates and laws, and federal brackets, Medicare 3.8% surcharge everybody's situation is different.
I am leery of articles like This Columbia one. touting a vague "tax equivalent yield" because one size does not fit all.
Don't forget, also ( which I am sure you didn't) that tax exempt dividends are added back to AGI in calculating the Medicare B premiums.

I sold all of my muni funds earlier this year because their yields were so low compared to other income investments— CDs, Treasuries, money markets, taxable bond funds, etc. They make no sense at current yields unless you are in a high tax bracket. We’ve been in the 12% bracket for a while, but munis had competitive yields until this year. Now they’re not competitive even if we bump up to the 22% bracket.

AAII Sentiment Survey, 8/30/23
BEARISH remained the top sentiment (34%; above average) & neutral remained the bottom sentiment (32.4%; above average); bullish remained the middle sentiment (33.1%; below average); Bull-Bear Spread was -1.4% (below average). Investor concerns: Inflation (still high); economy; the Fed; dollar; crypto regulations; market volatility (VIX, VXN, MOVE); Russia-Ukraine war (79+ weeks, 2/24/22-now); geopolitical. For the Survey week (Th-Wed), stocks were up, bonds up, oil up, gold up, dollar down. The SEC had recent setbacks in crypto lawsuits (vs Ripple, Grayscale); its "regulation by enforcement" approach was dented by courts. A class-action suit against Uniswap was also rejected. #AAII #Sentiment #Markets
LINK

I wrote two articles for the MFO newsletter this month. One is on municipal bond funds. Columbia Threadneedle Investments just published an article, "Municipal Bond Outlook". The author's conclusion which I agree with is:
"Historic tax-equivalent yields alone are a good enough reason to consider allocating into municipal bonds. Doing it in the current yield environment also allows investors to pursue a longer-term buffer against the potential for falling interest rates or the impacts of a recession."
https://seekingalpha.com/article/4631914-municipal-bond-outlook-we-think-positive-performance-will-continue
My article evaluates several quality municipal bond funds.

Fund Allocations (Cumulative), 7/31/23
There were noticeable shifts into stocks. The changes for OEFs + ETFs were based on a total AUM of about $31.60 trillion in the previous month, so +/- 1% change was about +/- $316.0 billion. Also note that these changes were from both fund inflows/outflows & price changes. #Funds #OEFs #ETFs #ICI
OEFs & ETFs: Stocks 59.44%, Hybrids 4.91%, Bonds 18.71%, M-Mkt 16.94%
https://ybbpersonalfinance.proboards.com/post/1159/thread

@davidrmoran: https://www.vox.com/2018/9/27/17911728/brett-kavanaugh-boof-definition-supreme-court

+1

@FD1000- Thanks for that link. It's very clear and instructive, and showed me a couple of Schwab pages that I hadn't stumbled across before.

3rd paragraph - I think you mean Ariel (not Artisan) International. (Fixed! Thanks!)
The next sentence leaves me confused: " Given that Morningstar doesn't track growth and value separately, and Bhansali is a distinctly contrarian, value investor, the star ratings might be a bit misleading. "
It used to be that M* lumped all the global stock funds together into one "world" category. That changed in 2021. There are now value, blend, and growth global catagories.
https://www.morningstar.com/funds/morningstar-world-stock-categories-get-some-style
And it used to be that funds got star ratings based on broad asset classes. That changed a long time ago. "In 2002, Morningstar enhanced the star rating with new peer groups and a new measure of risk-adjusted return. The peer groups for the rating were changed to the smaller category groups instead of the broad asset classes."
https://www.morningstar.com/content/dam/marketing/shared/research/foundational/780133_The_Morningstar_Rating_for_Funds__Analyzing_the_Performance_of_the_Star_Rating_Globally.pdf
@Shostakovich - you might take a look at LTTMX. Its long term figures (including risk) look similar to AGLOX 's. The two funds follow somewhat different paths, with Lipper classifying LTTMX as a global equity income fund in contrast classifying AGLOX as a global multi-cap value fund.
Portfolio Valuation comparison of the funds.
Which gets me back to confusion about value classifications. LTTMX is a value fund (M* classifies it as a global large cap value peer of AGLOX), while Lipper lumps all global equity income funds together. In the end, they both deliver similar results with similar risks using value oriented portfolios.
If one is willing to take on more risk (i.e. use a more volatile fund), one can find global value funds that more than reward the additional risk (i.e. have better risk-adjusted returns). But if risk management is paramount, LTTMX is worth a look.