The Patient Protection and Affordable Care Act (P.L. 111-148) and the Reconciliation Act of 2010 (P.L. 111-152) impose an annual fee on certain for-profit health insurers, starting in 2014. The aggregate amount of the ACA fee, to be collected across all covered insurers, will be $8.0 billion in 2014, $11.3 billion in 2015 and 2016, $13.9 billion in 2017, and $14.3 billion in 2018. After 2018, the aggregate fee will be indexed to the overall rate of annual premium growth, as calculated by the Internal Revenue Service. The annual fee will be apportioned among health insurers, based on (1) their market share and (2) their dollar value of business. The fee applies to net health care premiums written, which are defined in regulations as gross premiums from insurance sales minus refunds to enrollees under the medical loss ratio provisions of the ACA, certain commissions, and premiums ceded to reinsurers. Ceded premiums are premiums that an insurer transfers to a reinsurer, as payment for protection against defined market risks. The ACA fee does not apply to the first $25 million of net premiums written by a covered insurer.