The following table shows our estimated constrained lifetime value of commissions per approved member by product for the years ended December 31, 2018, 2017 and 2016:
For both Medicare Advantage and Medicare Part D prescription drug plans, we receive a fixed, annual commission payment from insurance carriers once the plan is approved by the carrier and either a fixed, monthly or annual commission payment beginning with and subsequent to the second plan year. Additionally, commission rates may be higher in the first twelve months of the plan if the plan is the first Medicare Advantage or Medicare Part D prescription drug plan issued to the member. In the first plan year of a Medicare Advantage and Medicare Part D prescription drug plan, after the health insurance carrier approves the application but during the effective year of the plan, we are paid a fixed commission that is prorated for the number of months remaining in the calendar year. Additionally, if the plan is the first Medicare Advantage or Medicare Part D plan issued to the member, we may receive a higher commission rate that covers a full twelve-month period, regardless of the month the plan was effective. We earn commission revenue for Medicare Advantage and Medicare Part D prescription drug plans for which we are the broker of record, typically until either the policy is cancelled or we otherwise do not remain the agent on the policy.
extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated with future commissions receivable from the plan is subsequently resolved. We evaluate the appropriateness of these constraints on at least an annual basis, including assessing factors affecting our estimate of the estimated lifetime value of commissions per approved member based on current trends impacting our business and assessing whether any adjustment to those constraints should be made. We update the assumptions when we observe a sufficient level of evidence that would suggest that the long term expectation of the assumption has changed.
2017 compared to 2016-Commission revenue decreased $0.4 million, or 0.2%, in 2017, due to a $19.1 million, or 31%, decrease in Individual, Family and Small Business commission revenue, partially offset by an $18.7 million, or 16% increase in Medicare commission revenue. The decrease in Individual, Family and Small Business commission revenue was primarily due to a 55% decline in individual and family health insurance approved members as of December 31, 2017 compared to December 31, 2016 due to the state of the individual and family health insurance plan market as a result of health care reform. The increase in Medicare commission revenue was primarily attributable to the increase in lifetime value of commissions per Medicare Supplement and Medicare Advantage approved members and an 8% increase in Medicare approved members as of December 31, 2017 compared to December 31, 2016, in part due to growth in our sale of Medicare Advantage and Medicare Supplement plans. Commission revenue was higher in the fourth quarter for both of the years ended December 31, 2017 and 2016 due to the seasonality of enrollments.
2018 compared 2017-Marketing and advertising expenses increased $17.1 million, or 26%, in 2018, primarily due to our investment in Medicare-related marketing initiatives partially offset by a decline in IFP-related marketing costs. In 2018 we saw increases of $9.5 million in variable advertising costs, $5.7 million in personnel costs due to additional headcount, and $1.2 million in stock-based compensation expenses. Marketing expenses were higher in the fourth quarter for both of the years ended December 31, 2018 and 2017 due to the seasonality of enrollments.
General and administrative expenses include compensation and benefits costs for staff working in our executive, finance, investor relations, government affairs, legal, human resources, internal audit, facilities and internal information technology departments. These expenses also include fees paid for outside professional services, including audit, tax, legal, government affairs and information technology fees.
2017 compared to 2016-For the year ended December 31, 2017, we recorded a benefit from income taxes of $33.7 million, representing an effective tax rate of 407.6%, which was higher than the statutory federal rate due primarily to the Tax Cuts and Jobs Act of 2017, or the Jobs Act, which was signed into law on December 22, 2017 resulting in significant changes to the Internal Revenue Code. The Jobs Act reduces the federal corporate income tax rate from 35% to 21% effective for tax periods beginning after December 31, 2017; changes U.S international taxation from a worldwide tax system to a territorial system; and imposes a one-time transition tax on untaxed cumulative foreign earnings and profits as of December 31, 2017. We calculated our best estimate of the impact of the Jobs Act in our 2017 year end income tax provision in accordance with our understanding of the Jobs Act as of the filing date of the 2017 10-K. The 2017 benefit from income taxes was largely due to the remeasurement of the net U.S. deferred tax liability based on the rate at which it is expected to reverse in the future, which resulted in a one-time benefit of $29.4 million. The 2017 benefit also includes a $1.7 million decrease in our liability for unrecognized tax benefits due to the expiration of the related statute of limitations. The remaining benefit of $2.6 million was impacted by research and development credits and stock-based compensation windfalls, partially offset by lobbying and other non-deductible expenses.
As discussed in Note 1 to the consolidated financial statements, the Company changed its method of accounting for revenue as a result of the full retrospective adoption of Accounting Standards Update (“ASU”) No. 2014-09 “Revenue from Contracts with Customers (Topic 606),” as amended.
Substantially all revenue for the years ended December 31, 2018, 2017 and 2016 was generated from customers located in the United States. Carriers representing 10% or more of our total revenue for the years ended December 31, 2018, 2017 and 2016 are presented in the table below: