This was a result of our nearly 12,000 teammates delivering creative risk management solutions for our customers.
We're also very proud that last week our Board of Directors authorized an increase of 10.8% in our quarterly dividend.
We delivered $770 million of revenue, growing 14.3% in total, and 8.5% organically.
Our EBITDAC margin grew by 280 basis points to 35.6% versus the third quarter of 2020.
Our net income per share for the third quarter was $0.52 on an as reported basis and $0.58, excluding the change in estimated acquisition earn-out payables.
As the year-to-date results are the best in our history, 10.8% internal growth year-to-date.
Rate increases remain relatively consistent with prior quarters, admitted market rates continue to be up 3% to 8% across most lines, the outliers or workers' compensation rates, which are down 1% to 3%, and commercial auto rates which were up 5% to 10%.
From an E&S perspective, most rates were up 10% to 20% with some outliers.
Coastal property both wind and quake, are up 10% to 30%, with this being a slightly broader range than we saw in the previous quarter.
Professional liability for most accounts remained very challenging with rates up 10% to 15%-plus, cyber-rates in some instances could increase dramatically depending on the security in place with the customer.
From an M&A perspective, we were successful in closing seven transactions during the quarter, with annual revenues of approximately $21 million.
We've closed a total of 11 deals year-to-date with annual revenues of $65 million have already announced a couple of additional acquisitions in October.
Retail delivered great results with organic revenue growth of 8.3% for the third quarter.
National Programs delivered another outstanding quarter, growing 13.2% organically.
The Wholesale Brokerage segment delivered 5.1% organic growth with commercial brokerage and binding performing well, driven by new business and continued rate increases for most lines of coverage.
The Services segment delivered organic revenue growth of 0.5%.
For the third quarter, we delivered total revenue growth of $96.3 million or 14.3% and organic revenue growth of 8.5%.
Income before income taxes and EBITDAC both increased by approximately 24%.
EBITDAC margins expanded 280 basis points, driven by strong organic revenue growth and managing our expenses.
Net income increased by $12.4 million or 9.3% and our diluted net income per share increased by 10.6% to $0.52.
The effective tax rate increased to 25.5% for the third quarter of this year as compared to 15.5% in the third quarter of last year.
We continue to anticipate our full year effective tax rate for 2021 will be in the 23% to 24% range.
Our weighted average number of shares increased slightly compared to the prior year and our dividends per share increased to $0.093 or 9.4% compared to the third quarter 2020.
The change in estimated acquisition earn-out payables was a charge of $23.1 million in the third quarter of this year compared to $15.3 million for the same period last year.
Excluding these non-cash items, income before income taxes on an adjusted basis, increased by 26.4%.
Our net income on an adjusted basis increased by $16.7 million or 11.4%.
And our adjusted diluted net income per share was $0.58, increasing 11.5%.
For the quarter, our total commissions and fees increased by 14.6% and our contingent commissions and GSCs increased by 27.1% as we qualify for certain additional contingents and GSCs this year.
Organic revenue, which excludes the net impact of M&A activity and changes in foreign exchange rates increased by 8.5%.
The Retail segment delivered total revenue growth of 17.8%, driven by acquisition activity over the past 12 months and organic revenue growth of 8.3% with solid growth across all lines of business.
EBITDAC margin for the quarter increased by 180 basis points and EBITDAC grew 24.6%, due to higher organic revenue growth, increased contingent commissions and GSCs, and managing our expenses even with slightly higher variable cost.
Our National Programs segment increased total revenue by 13.7% and organic revenue by 13.2%.
In conjunction with the onboarding of a new customer, we recognized approximately $5 million of incremental revenue this quarter that represents timing.
EBITDAC increased by $18.7 million or 28.5% with the margin improving 510 basis points, as a result of strong organic revenue growth, managing our expenses and the positive impact of the non-recurring write-off of certain receivables that occurred in the third quarter of last year.
The Wholesale Brokerage segment delivered total revenue growth of 11.2% driven by acquisitions in the past 12 months and organic revenue growth of 5.1%.
EBITDAC grew 4.7%, but the growth was impacted by incremental broker compensation driven by higher levels of performance, slightly higher variable cost and certain non-recurring intercompany IT charges.
Our Services segment increased total revenue and organic revenue by 0.5% with EBITDAC growing 6.8%, driven by continued management of our expenses.
We experienced another strong quarter of cash flow generation and have delivered $628 million of cash flow from operations through the first nine months of this year, growing $88 million or 16% as compared to the first nine months of last year.
Our ratio of cash flow from operations as a percentage of total revenue remained strong at 27% for the first nine months of this year.

Summary:
Our net income per share for the third quarter was $0.52 on an as reported basis and $0.58, excluding the change in estimated acquisition earn-out payables.
For the third quarter, we delivered total revenue growth of $96.3 million or 14.3% and organic revenue growth of 8.5%.
Net income increased by $12.4 million or 9.3% and our diluted net income per share increased by 10.6% to $0.52.
And our adjusted diluted net income per share was $0.58, increasing 11.5%.