increased by approximately $61,000, or 16.9%, as a result of proceeding with discretionary projects in 2012 that were delayed in 2011. Board of Directors expense increased by approximately $199,000, or 33.1%, primarily due to a 16.2% increase in the book value of directors deferred compensation restricted share awards. In addition, bad debt expense increased by approximately $42,000 as the result of certain employer group receivable balances that were determined to be uncollectable. Also, miscellaneous expenses increased by approximately $32,000 due to the one-time costs incurred relative to the refinancing of our office building.
A summary of our future commitments as of December 31, 2013 is as follows:
with the dental service providers, and (iv) the Company is involved in the determination of dental service specifications. Self-insured premium revenue is recognized upon the payment of claims for self-insured members in accordance with agreements with self-insured employers and is included in premium revenue in the accompanying consolidated statements of comprehensive income.
corporate bonds was approximately 2.94% at December 31, 2013. The weighted average maturity of our investment grade corporate bonds was 5.68 years at December 31, 2013. The unrealized gains and losses on available-for-sale investments are due to a change in fair value for these investments caused primarily by changes in prevailing interest rates since they were purchased. There were no material realized gains or losses for the year ended December 31, 2013. There was approximately $40,000 of realized gains related to investments for the year ended December 31, 2012.
The components of the provision for income taxes are summarized as follows for the years ended December 31, 2013, 2012 and 2011, respectively:
Share-based compensation cost is measured at the grant date based on the fair value of the liability awards and is recognized as expense ratably over the vesting periods and is included in other insurance expense in the consolidated statements of comprehensive income. The fair value of the liability awards is remeasured at the end of each reporting period through the remaining vesting period with the change in fair value recognized in earnings currently.
awards. In 2013, key employees were granted 204 share awards. As of December 31, 2013, the Company granted a total of 2,740 share awards, net of forfeitures and rescinded share awards.
The following is a summary of activity of vested awards for the years ended December 31, 2013 and 2012:
GAAP differs in certain respects from the accounting practices prescribed or permitted by state insurance regulatory authorities (“statutory-basis”), a non-GAAP basis of accounting. The statutory-basis net income for Dental Care Plus was approximately $1,191,000, $1,108,000, and $703,000 for the years ended December 31, 2013, 2012 and 2011, respectively. Statutory-basis equity was approximately $8,560,000 and $7,396,000 at December 31, 2013 and 2012, respectively.
Leases-The Company leases certain equipment and office space under non-cancelable operating leases. Rent expense under all operating leases was approximately $136,000, $118,000, and $231,000 for the years ended December 31, 2013, 2012 and 2011, respectively.
In accordance with the provisions of the Affordable Care Act of 2010, effective January 1, 2014, the federal government imposed an annual assessment on all U.S. health insurers of approximately $8 billion in 2014. This annual assessment will increase each year and is expected to be $14.3 billion in 2018. This annual assessment is allocated to individual health insurers based on the ratio of the insurer’s net premiums written during the preceding calendar year to the total health insurance premiums for any U.S. risk premium written for that same year. The first $25 million of a health insurer’s net premium written is exempt from the federal premium tax assessment. The net premium written by a health insurer from $25 million to $50 million is subject to 50% of the federal premium tax rate. Accordingly, in January of 2014, the Company established a liability for the federal premium tax of approximately $334,000 that is payable to the United States Treasury in September 2014, along with an offsetting asset that will be amortized during 2014.