Century Bancorp posted an 11.4 percent increase in net income for the quarter ended June 30, increasing profits to $5.6 million from $5 million in the year-ago period.

The holding company for Medford-based Century Bank also increased its total assets 3.7 percent to $3.6 billion from $3.4 billion at Dec. 31, 2013.

Net interest income increased 14.5 percent year over year to $33.3 million for the six-month period ended June 30.

The company decreased its provision for loan losses by $450,000 from $1.5 million to $1.1 million during that same period, largely due to changes in its portfolio composition and changes in qualitative economic factors.

The provision for loan losses decreased by $450,000 from $1.5 million for the six months ended June 30, 2013 to $1.1 million for the same period in 2014, primarily as a result of changes in the portfolio composition and changes in qualitative economic factors. There were no realized gains on sales of investments for the six months ended June 30, as compared with $1.7 million for the same period in 2013. The company’s effective tax rate decreased from 5.8 percent in 2013 to 4.7 percent in 2014 primarily as a result of an increase in tax-exempt income.

The company’s allowance for loan losses totaled $21.7 million or 1.65 percent of loans outstanding at June 30, compared with $20.5 million or 1.76 percent of loans outstanding at the same time last year. The increase in the allowance for loan losses was due to the increase in the size of the loan portfolio. Non-performing assets totaled $2.8 million at June 30, compared with $3.3 million last year.

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 its Class B common stock. The dividends were declared payable Aug. 15 to stockholders of record on Aug. 1.