Increased assets and net interest income boosted Century Bancorp Inc.’s earnings by 14 percent as net income rose to $14.26 million for the nine months ended Sept. 30, compared to net income of $12.5 million during the same period a year ago.

Total assets increased 8.1 percent to $3 billion at Sept. 30, up from $2.7 billion at Dec. 31, 2011. For the quarter ended Sept. 30, net income totaled $5.7 million, a 24 percent increase compared to net income of $4.6 million for the same period a year ago.

Net interest income totaled $47 million for the first nine months of 2012, compared to $41.3 million for the same period in 2011. The 13.9 percent increase in net interest income for the period is due to a 10.5 percent increase in the average balances of earning assets, combined with a similar increase in average deposits.

The company’s board of directors voted a regular quarterly dividend of 12 cents per share on the company’s Class A common stock, and 6 cents per share on the company’s Class B common stock. The dividends were declared payable Nov. 15 to stockholders of record on Nov. 1.