Exhibit 99.1

For Immediate Release

Isabella Bank Corporation

401 North Main Street

Mt. Pleasant, MI 48858-1649

FOR MORE INFORMATION CONTACT:

Trish Tomczak, Director of Marketing

Phone: 989-779-6333 Fax: 989-775-5501

Isabella Bank Corporation Announces First Quarter 2023 Earnings

Solid start to 2023; net income of $5.3 million

Mt. Pleasant, Michigan, April 20, 2023 — Isabella Bank Corporation (the “Corporation”) (OTCQX: ISBA) announced strong earnings results for the first quarter of 2023. The Corporation reported net income of $5.3 million and earnings per common share of $0.70, both substantial increases from the same period in 2022.

First Quarter 2023 Highlights:

•Net income increased 12% to $5.3 million, compared to first quarter 2022.

•Net interest income improved 14%, compared to first quarter 2022.

•Deposits grew more than $69 million, or 4%, from December 31, 2022.

•Shareholders earned a cash dividend of $0.28 per share, with an annualized dividend yield of 4.52%, as of March 31, 2023.

The Corporation’s significant growth in net interest income results largely from a combination of increased interest rates and growth in its loan portfolio. Those more than offset a climb in interest expense that accompanied a quarter of excellent growth in deposits.

“We are very pleased with our first quarter operating results,” said Jae A. Evans, President and Chief Executive Officer. “Isabella Bank's stability as a community bank and its already strong liquidity position were further enhanced in the quarter, in sharp contrast to challenges elsewhere in the banking sector.

“Isabella Bank's continued growth reflects our complete suite of financial products and services delivered by staff customers trust,” Evans said. “Significantly, we opened a full-service branch in Saginaw at the end of March — our fifth branch in Saginaw County. This growth in our footprint demonstrates our role and commitment to consumer and business customers as a prominent, independent community bank.”

Operating Results

Net income: Net income for first quarter 2023 was $5.3 million, compared to $4.7 million in the first quarter of 2022, increasing 12.4%. Earnings per common share were $0.70 for the first quarter of 2023, above the $0.63 reported for the same period in 2022.

Net interest income: Net interest income for first quarter 2023 increased $1.9 million, or 13.9%, compared to the same period in 2022. Rising rates on loans and investment securities led to a $3.8 million increase in gross interest income. However, the combination of continued growth in deposits and rising interest rates led to a $2.0 million increase in interest expense during the quarter.

Noninterest income and expenses: Noninterest income decreased $254,000 during the first quarter of 2023 compared to the same period in 2022. The decline was mainly driven by a $300,000 reduction in mortgage servicing rights, as rising interest rates have led to a decline in both the volume and balance of loans serviced. Noninterest expenses increased $878,000, primarily the result of increased compensation, professional services, and FDIC insurance expense.

Net yield on interest earning assets: The Corporation’s fully taxable equivalent net yield on interest earning assets was 3.22% for the first quarter of 2023, compared to 2.86% for the same period in 2022. The marked improvement is the result of the implementation of strategic programs focused on improving the net yield in a rising rate environment, which included a reduced reliance on higher-cost borrowed funds and brokered deposits.

Balance Sheet

Assets: Total assets were $2.1 billion and assets under management were $2.92 billion as of March 31, 2023. Managed assets includes loans sold and serviced of $259.5 million as well as $571.5 million in investment and trust assets managed by Isabella Wealth.

Loans: Loans outstanding as of March 31, 2023 totaled $1.3 billion. During the first quarter, gross loans increased $6.5 million primarily due to growth within the commercial and consumer portfolios. The adherence to strong underwriting standards continued to be reflected in the low levels of total past due and nonaccrual loans, which were $6.1 million, or 0.48% of total loans, at the end of the period.

Deposits: Total deposits increased $69.3 million, or 3.97%, since December 31, 2022, driven by growth in money market and CD accounts, in addition to new customer relationships.

Capital: The Bank is considered a “well-capitalized” institution, as its capital ratios exceeded the minimum designated requirements. As of March 31, 2023, the Bank’s Tier 1 Leverage Ratio was 9.25%, Tier 1 Capital Ratio was 13.73%, and Total Capital Ratio was 14.67%. The minimum requirements to be considered well capitalized are a Tier 1 Leverage Ratio of 5.0%, Tier 1 Capital Ratio of 8.0%, and Total Capital Ratio of 10.0%.

Dividend: During the first quarter of 2023, the Corporation paid a $0.28 per common share cash dividend. Based on the Corporation’s closing stock price of $24.80 as of March 31, 2023, the annualized cash dividend yield was 4.52%.

About the Corporation

Isabella Bank Corporation (OTCQX: ISBA) is the parent holding company of Isabella Bank, a state chartered community bank headquartered in Mt. Pleasant, Michigan. Isabella Bank was established in 1903 and has been committed to serving the local banking needs of its customers and communities for 120 years. The Bank offers personal and commercial lending and deposit products, as well as investment, trust, and estate planning services through Isabella Wealth. The Bank has locations throughout seven Mid-Michigan counties: Clare, Gratiot, Isabella, Mecosta, Midland, Montcalm, and Saginaw.

For more information about Isabella Bank Corporation, visit the Investor Relations link at www.isabellabank.com. Isabella Bank Corporation common stock is quoted on the OTCQX tier of the OTC Markets Group, Inc.’s electronic quotation system (www.otcmarkets.com) under the symbol “ISBA.” The Corporation’s investor relations firm is Renmark Financial Communications, Inc. (www.renmarkfinancial.com).

Forward-Looking Statements

This press release includes forward-looking statements. To the extent that the foregoing information refers to matters that may occur in the future, please be aware that such forward-looking statements may differ materially from the actual results. Additional information concerning some of the factors that could cause materially different results is included in the sections titled “Risk Factors” and “Forward Looking Statements” set forth in Isabella Bank Corporation’s filings with the Securities and Exchange Commission, which are available from the Securities and Exchange Commission’s Public Reference facilities and from its website at www.sec.gov.

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED)

(Dollars in thousands)

			March 31 2023						December 31 2022
ASSETS
Cash and cash equivalents
Cash and demand deposits due from banks			$	21,987					$	27,420
Fed Funds sold and interest bearing balances due from banks			76,736						11,504
Total cash and cash equivalents			98,723						38,924
Available-for-sale securities, at fair value			568,650						580,481
Mortgage loans available-for-sale			171						379
Loans			1,270,651						1,264,173
Less allowance for credit losses			12,640						9,850
Net loans			1,258,011						1,254,323
Premises and equipment			26,304						25,553
Corporate owned life insurance policies			33,208						32,988
Equity securities without readily determinable fair values			15,746						15,746
Goodwill and other intangible assets			48,286						48,287
Accrued interest receivable and other assets			35,525						33,586
TOTAL ASSETS			$	2,084,624					$	2,030,267
LIABILITIES AND SHAREHOLDERS’ EQUITY
Deposits
Noninterest bearing			$	478,829					$	494,346
Interest bearing demand deposits			383,602						372,155
Certificates of deposit under $250 and other savings			867,435						810,642
Certificates of deposit over $250			83,662						67,132
Total deposits			1,813,528						1,744,275
Borrowed funds
Federal funds purchased and repurchase agreements			31,995						57,771
Subordinated debt, net of unamortized issuance costs			29,267						29,245
Total borrowed funds			61,262						87,016
Accrued interest payable and other liabilities			16,501						12,766
Total liabilities			1,891,291						1,844,057
Shareholders’ equity
Common stock — no par value 15,000,000 shares authorized; issued and outstanding 7,540,015 shares (including 175,663 shares held in the Rabbi Trust) in 2023 and 7,559,421 shares (including 154,879 shares held in the Rabbi Trust) in 2022			127,717						128,651
Shares to be issued for deferred compensation obligations			5,344						5,005
Retained earnings			90,586						89,748
Accumulated other comprehensive income (loss)			(30,314)						(37,194)
Total shareholders’ equity			193,333						186,210
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY			$	2,084,624					$	2,030,267

CONDENSED CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED)

(Dollars in thousands except per share amounts)

			Three Months Ended   March 31
			2023						2022
Interest income
Loans, including fees			$	14,889					$	12,378
Available-for-sale securities
Taxable			2,502						1,615
Nontaxable			718						660
Federal funds sold and other			486						109
Total interest income			18,595						14,762
Interest expense
Deposits			2,829						936
Borrowings
Federal funds purchased and repurchase agreements			149						9
Federal Home Loan Bank advances			—						72
Subordinated debt, net of unamortized issuance costs			266						266
Total interest expense			3,244						1,283
Net interest income			15,351						13,479
Provision for credit losses			41						37
Net interest income after provision for credit losses			15,310						13,442
Noninterest income
Service charges and fees			1,978						2,209
Wealth management fees			786						754
Earnings on corporate owned life insurance policies			226						210
Net gain on sale of mortgage loans			67						224
Other			236						150
Total noninterest income			3,293						3,547
Noninterest expenses
Compensation and benefits			6,589						6,074
Furniture and equipment			1,597						1,450
Occupancy			1,005						966
Other			3,007						2,830
Total noninterest expenses			12,198						11,320
Income before federal income tax expense			6,405						5,669
Federal income tax expense			1,084						935
NET INCOME			$	5,321					$	4,734
Earnings per common share
Basic			$	0.70					$	0.63
Diluted			$	0.70					$	0.62
Cash dividends per common share			$	0.28					$	0.27

AVERAGE BALANCES, INTEREST RATE, AND NET INTEREST INCOME (UNAUDITED)

(Dollars in thousands)

The following schedules present the daily average amount outstanding for each major category of interest earning assets, non-earning assets, interest bearing liabilities, and noninterest bearing liabilities. These schedules also present an analysis of interest income and interest expense for the periods indicated. All interest income is reported on a fully taxable equivalent (FTE) basis using a federal income tax rate of 21%. Loans in nonaccrual status, for the purpose of the following computations, are included in the average loan balances. Federal Reserve Bank (FRB) and Federal Home Loan Bank (FHLB) restricted equity holdings are included in other interest earning assets.

			Three Months Ended
			March 31, 2023																		March 31, 2022
			Average Balance						Tax Equivalent Interest						Average Yield / Rate						Average Balance						Tax Equivalent Interest						Average Yield / Rate
INTEREST EARNING ASSETS
Loans			$	1,268,269					$	14,889					4.70		%				$	1,235,788					$	12,378					4.01		%
Taxable investment securities			504,889						2,471						1.96		%				421,503						1,615						1.53		%
Nontaxable investment securities			106,240						1,021						3.84		%				101,604						920						3.62		%
Fed funds sold			17						—						4.50		%				3						—						0.06		%
Other			60,583						486						3.21		%				163,353						109						0.27		%
Total earning assets			1,939,998						18,867						3.89		%				1,922,251						15,022						3.13		%
NONEARNING ASSETS
Allowance for credit losses			(12,660)																		(9,128)
Cash and demand deposits due from banks			25,039																		26,839
Premises and equipment			25,864																		24,461
Accrued income and other assets			71,063																		102,805
Total assets			$	2,049,304																	$	2,067,228
INTEREST BEARING LIABILITIES
Interest bearing demand deposits			$	379,717					$	146					0.15		%				$	383,474					$	50					0.05		%
Savings deposits			645,987						1,466						0.91		%				615,335						159						0.10		%
Time deposits			267,463						1,217						1.82		%				290,146						727						1.00		%
Federal funds purchased and repurchase agreements			39,709						149						1.50		%				49,058						9						0.07		%
Federal Home Loan Bank advances			—						—						—		%				14,889						72						1.93		%
Subordinated debt, net of unamortized issuance costs			29,253						266						3.64		%				29,166						266						3.65		%
Total interest bearing liabilities			1,362,129						3,244						0.95		%				1,382,068						1,283						0.37		%
NONINTEREST BEARING LIABILITIES
Demand deposits			486,491																		458,343
Other			13,094																		16,898
Shareholders’ equity			187,590																		209,919
Total liabilities and shareholders’ equity			$	2,049,304																	$	2,067,228
Net interest income (FTE)									$	15,623																	$	13,739
Net yield on interest earning assets (FTE)															3.22		%																2.86		%

SELECTED FINANCIAL DATA (UNAUDITED)

(Dollars in thousands except per share amounts)

			Three Months Ended
			March 31 2023						March 31 2022						March 31 2021
PER SHARE
Basic earnings			$	0.70					$	0.63					$	0.68
Diluted earnings			$	0.70					$	0.62					$	0.67
Dividends			$	0.28					$	0.27					$	0.27
Tangible book value			$	19.24					$	19.56					$	21.35
Quoted market value
High			$	25.10					$	26.00					$	22.50
Low			$	22.08					$	24.50					$	19.45
Close (1)			$	24.80					$	25.85					$	21.75
Common shares outstanding (1)			7,540,015						7,542,758						7,958,883
Average number of common shares outstanding			7,556,585						7,533,711						7,969,462
Average number of diluted common shares outstanding			7,634,417						7,639,688						8,088,524
PERFORMANCE RATIOS
Return on average total assets			1.04		%				0.92		%				1.09		%
Return on average shareholders' equity			11.35		%				9.02		%				9.78		%
Return on average tangible shareholders' equity			15.28		%				11.72		%				12.53		%
Net interest margin yield (FTE)			3.22		%				2.86		%				2.98		%
ASSETS UNDER MANAGEMENT (1)
Loans sold with servicing retained			$	259,512					$	275,556					$	298,514
Assets managed by Isabella Wealth			$	571,453					$	501,829					$	454,459
Total assets under management			$	2,915,589					$	2,838,318					$	2,768,405
ASSET QUALITY (1)
Nonaccrual loans			$	488					$	747					$	4,532
Foreclosed assets			$	414					$	187					$	384
Net loan charge-offs (recoveries)			$	(9)					$	(64)					$	(50)
Nonperforming loans to gross loans			0.04		%				0.06		%				0.38		%
Nonperforming assets to total assets			0.05		%				0.05		%				0.26		%
Allowance for credit losses to gross loans			0.99		%				0.76		%				0.78		%
CAPITAL RATIOS (1)
Shareholders' equity to assets			9.27		%				9.50		%				10.83		%
Tier 1 leverage			8.58		%				8.12		%				8.56		%
Common equity tier 1 capital			12.71		%				12.83		%				13.77		%
Tier 1 risk-based capital			12.71		%				12.83		%				13.77		%
Total risk-based capital			15.77		%				15.84		%				14.54		%

(1) At end of period

SUPPLEMENTAL BALANCE SHEET DATA (UNAUDITED)

(Dollars in thousands)

			March 31 2023						December 31 2022						September 30 2022						June 30 2022						March 31 2022
Commercial			$	755,595					$	744,440					$	730,504					$	772,567					$	727,614
Agricultural			94,760						104,985						96,850						94,726						88,169
Residential real estate			336,186						336,694						334,412						329,795						328,559
Consumer			84,110						78,054						74,385						74,822						74,029
Gross loans			$	1,270,651					$	1,264,173					$	1,236,151					$	1,271,910					$	1,218,371

			March 31 2023						December 31 2022						September 30 2022						June 30 2022						March 31 2022
Noninterest bearing demand deposits			$	478,829					$	494,346					$	510,127					$	488,110					$	461,473
Interest bearing demand deposits			383,602						372,155						368,537						370,284						387,187
Savings deposits			662,495						625,734						651,129						635,397						635,195
Certificates of deposit			288,103						251,541						260,741						265,477						279,708
Internet certificates of deposit			499						499						499						598						598
Total deposits			$	1,813,528					$	1,744,275					$	1,791,033					$	1,759,866					$	1,764,161

			March 31 2023						December 31 2022						September 30 2022						June 30 2022						March 31 2022
U.S. Treasury			$	212,086					$	208,701					$	206,791					$	214,474					$	218,268
States and political subdivisions			108,719						117,512						114,000						119,649						114,015
Auction rate money market preferred			2,716						2,342						2,479						2,497						2,867
Mortgage-backed securities			37,797						39,070						41,042						45,796						49,578
Collateralized mortgage obligations			200,252						205,728						209,720						167,572						152,441
Corporate			7,080						7,128						7,201						7,602						7,750
Available-for-sale securities, at fair value			$	568,650					$	580,481					$	581,233					$	557,590					$	544,919

			March 31 2023						December 31 2022						September 30 2022						June 30 2022						March 31 2022
Securities sold under agreements to repurchase without stated maturity dates			$	31,995					$	57,771					$	52,479					$	47,247					$	51,353
Federal Home Loan Bank advances			—						—						—						10,000						10,000
Subordinated debt, net of unamortized issuance costs			29,267						29,245						29,225						29,203						29,181
Total borrowed funds			$	61,262					$	87,016					$	81,704					$	86,450					$	90,534

SUPPLEMENTAL STATEMENTS OF INCOME DATA (UNAUDITED)

(Dollars in thousands)

			Three Months Ended March 31
			2023						2022
Service charges and fees
ATM and debit card fees			$	1,160					$	1,093
Service charges and fees on deposit accounts			611						609
Freddie Mac servicing fee			159						171
Net mortgage servicing rights income (loss)			(36)						264
Other fees for customer services			84						72
Total service charges and fees			1,978						2,209
Wealth management fees			786						754
Earnings on corporate owned life insurance policies			226						210
Net gain on sale of mortgage loans			67						224
Other			236						150
Total noninterest income			$	3,293					$	3,547

			Three Months Ended March 31
			2023						2022
Compensation and benefits			$	6,589					$	6,074
Furniture and equipment			1,597						1,450
Occupancy			1,005						966
Other
Audit, consulting, and legal fees			535						549
ATM and debit card fees			400						434
Marketing costs			245						239
Memberships and subscriptions			240						217
FDIC insurance premiums			228						125
Loan underwriting fees			215						182
Director fees			204						201
Donations and community relations			184						287
All other			756						596
Total other noninterest expenses			3,007						2,830
Total noninterest expenses			$	12,198					$	11,320