million in the prior quarter. The fully taxable equivalent efficiency ratio was 65.3% at March 31, 2022, compared to 59.7% at December 31, 2021.
Income tax expense totaled $3.6 million during the first quarter, compared to $5.3 million. The effective tax rate for the first quarter 2022 was 16.4%, compared to 18.6% for the full year 2021. The lower rate compared to the statutory rate reflects the continued success of our tax strategies and tax-exempt income.
Capital
Capital ratios continue to be strong and in excess of federal bank regulatory agency “well capitalized” thresholds. The Tier 1 leverage ratios at March 31, 2022 for the consolidated company and NBH Bank were 10.48% and 9.09%, respectively. Shareholders’ equity totaled $820.2 million at March 31, 2022, decreasing $19.9 million primarily due to a higher accumulated other comprehensive loss.
Common book value per share decreased $0.71 to $27.33 at March 31, 2022. Tangible common book value per share decreased $0.69 to $23.64 at March 31, 2022 as this quarter’s earnings, net of dividends paid, were outpaced by the increase in accumulated other comprehensive loss. Excluding accumulated other comprehensive loss, the tangible book value per share increased $0.37 to $24.93 at March 31, 2022.
Year-Over-Year Review
(All comparisons refer to the first quarter 2021, except as noted)
Net income totaled $18.4 million, or $0.60 per diluted share, for the first quarter of 2022, compared to $26.8 million, or $0.86 per diluted share for the first quarter of 2021. The decrease was largely due to $12.7 million lower mortgage banking income, due to lower refinance activity in 2022. The return on average tangible assets was 1.07%, compared to 1.65% in the same period prior year, and the return on average tangible common equity was 10.31%, compared to 15.20%.
Fully taxable equivalent net interest income totaled $48.0 million, an increase of $1.5 million or 3.2%. Average earning assets increased $464.6 million, or 7.4%, including originated loan growth of $356.9 million. The fully taxable equivalent net interest margin narrowed 12 basis points to 2.90%, due to lower earning asset yields, which were partially offset by a decrease in the cost of funds. The yield on earning assets decreased 20 basis points driven by lower PPP loan forgiveness activity. The cost of deposits decreased 11 basis points to a record low 0.17%.
Loans outstanding totaled $4.7 billion, increasing $371.0 million or 8.6%. Excluding PPP loans of $7.6 million and $217.7 million for the first quarters 2022 and 2021 respectively, total loans increased $581.0 million or 14.2%, led by commercial loan growth of $534.6 million, or 19.4%. New loan fundings over the trailing 12 months totaled a record $1.7 billion, led by commercial loan fundings of $1.2 billion.
The Company recorded $0.3 million of provision release during the first quarter, compared to a provision release of $3.6 million in the same period last year. The provision release was driven by strong asset quality and an improved outlook in the CECL model’s underlying economic forecast. Net charge-offs totaled 0.05% of total loans, compared to 0.01% of total loans in the same period last year. Non-performing loans to total loans improved 14 basis points to 0.24% at March 31, 2022. The allowance for credit losses totaled 1.04% of total loans, compared to 1.28% at March 31, 2021.
Average total deposits increased $413.4 million or 7.2%, to $6.2 billion. Average non-interest bearing demand deposits increased $268.3 million or 12.4%, and average transaction deposits increased $559.0 million, or 11.6%. The mix of transaction deposits to total deposits increased by 319 basis points to 87.4%, and the mix of non-interest bearing demand deposits to total deposits improved 189 basis points to 40.1% at March 31, 2022.
Non-interest income totaled $19.1 million, a decrease of $14.3 million or 42.9%, driven by $12.7 million lower mortgage banking income due to lower refinance activity in 2022, as well as competition driving tighter gain on sale margins. Other non-interest income