(a) A lawyer shall not make an agreement for, charge, or collect an unreasonable fee or an unreasonable amount for expenses. The factors to be considered in determining the reasonableness of a fee include the following:
(1) the time and labor required, the novelty and difﬁculty of the questions involved, and the skill requisite to perform the legal service properly;
(2) the likelihood, if apparent to the client, that the acceptance of the particular employment will preclude other employment by the lawyer;
(3) the fee customarily charged in the locality for similar legal services;
(4) the amount involved and the results obtained;
(5) the time limitations imposed by the client or by the circumstances;
(6) the nature and length of the professional relationship with the client;
(7) the experience, reputation, and ability of the lawyer or lawyers performing the services; and
(8) whether the fee is ﬁxed or contingent.
(b) When the lawyer has not regularly represented the client, the basis or rate of the fee and expenses shall be communicated to the client, in writing, before or within a reasonable time after commencing the representation. Any changes in the basis or rate of the fee or expenses shall also be promptly communicated to the client, in writing.
(c) A fee may be contingent on the outcome of the matter for which the service is rendered, except in a matter in which a contingent fee is otherwise prohibited. A contingent fee agreement shall meet all of the requirements of Chapter 23.3 of the Colorado Rules of Civil Procedure, “Rules Governing Contingent Fees.”
(d) Other than in connection with the sale of a law practice pursuant to Rule 1.17, a division of a fee between lawyers who are not in the same ﬁrm may be made only if:
(1) the division is in proportion to the services performed by each lawyer or each lawyer assumes joint responsibility for the representation;
(2) the client agrees to the arrangement, including the basis upon which the division of fees shall be made, and the client’s agreement is conﬁrmed in writing; and
(3) the total fee is reasonable.
(e) Referral fees are prohibited.
(f) Fees are not earned until the lawyer confers a beneﬁt on the client or performs a legal service for the client. Advances of unearned fees are the property of the client and shall be deposited in the lawyer’s trust account pursuant to Rule 1.15B(a)(1) until earned. If advances of unearned fees are in the form of property other than funds, then the lawyer shall hold such property separate from the lawyer’s own property pursuant to Rule 1.15A(a).
(g) Nonrefundable fees and nonrefundable retainers are prohibited. Any agreement that purports to restrict a client’s right to terminate the representation, or that unreasonably restricts a client’s right to obtain a refund of unearned or unreasonable fees, is prohibited.
Source: (b) and Comment amended April 20, 2000, effective July 1, 2000; (d) amended and adopted April 18, 2001, effective July 1, 2001; entire rule and Comment amended and adopted May 30, 2002, effective July 1, 2002; entire Appendix repealed and readopted April 12, 2007, effective January 1, 2008; Comment  amended and effective November 6, 2008; (b) amended and Comment [3A] repealed March 10, 2011, effective July 1, 2011; (f) amended and Comments  and  amended, effective April 6, 2016.
Reasonableness of Fee and Expenses
 Paragraph (a) requires that lawyers charge fees that are reasonable under the circumstances. The factors speciﬁed in (1) through (8) are not exclusive. Nor will each factor be relevant in each instance. Paragraph (a) also requires that expenses for which the client will be charged must be reasonable. A lawyer may seek reimbursement for the cost of services performed in-house, such as copying, or for other expenses incurred in-house, such as telephone charges, either by charging a reasonable amount to which the client has agreed in advance or by charging an amount that reasonably reﬂects the cost incurred by the lawyer.
Basis or Rate of Fee
 When the lawyer has regularly represented a client, they ordinarily will have evolved an understanding concerning the basis or rate of the fee and the expenses for which the client will be responsible. In a new client-lawyer relationship, the basis or rate of the fee must be promptly communicated in writing to the client. When the lawyer has regularly represented a client, they ordinarily will have reached an understanding concerning the basis or rate of the fee; but, when there has been a change from their previous understanding, the basis or rate of the fee should be promptly communicated in writing. All contingent fee arrangements must be in writing, regardless of whether the client-lawyer relationship is new or established. See C.R.C.P., Ch. 23.3, Rule 1. A written communication must disclose the basis or rate of the lawyer’s fees, but it need not take the form of a formal engagement letter or agreement, and it need not be signed by the client. Moreover, it is not necessary to recite all the factors that underlie the basis of the fee, but only those that are directly involved in its computation. It is sufﬁcient, for example, to state that the basic rate is an hourly charge or a ﬁxed amount or an estimated amount, to identify the factors that may be take into account in ﬁnally ﬁxing the fee, or to furnish the client with a simple memorandum or the lawyer’s customary fee schedule. When developments occur during the representation that render an earlier disclosure substantially inaccurate, a revised written disclosure should be provided to the client.
 Contingent fees, like any other fees, are subject to the reasonableness standard of paragraph (a) of this Rule. In determining whether a particular contingent fee is reasonable, or whether it is reasonable to charge any form of contingent fee, a lawyer must consider the factors that are relevant under the circumstances. Applicable law may impose limitations on contingent fees, such as a ceiling on the percentage allowable, or may require a lawyer to offer clients an alternative basis for the fee. Applicable law also may apply to situations other than a contingent fee, for example, government regulations regarding fees in certain tax matters.
Terms of Payment
 A lawyer may require advance payment of a fee, but is obliged to return any unearned portion. See Rule 1.16(d). A lawyer may accept property in payment for services, such as an ownership interest in an enterprise, providing this does not involve acquisition of a proprietary interest in the cause of action or subject matter of the litigation contrary to Rule 1.8(i). However, a fee paid in property instead of money may be subject to the requirements of Rule 1.8(a) because such fees often have the essential qualities of a business transaction with the client.
 An agreement may not be made whose terms might induce the lawyer improperly to curtail services for the client or perform them in a way contrary to the client’s interest. For example, a lawyer should not enter into an agreement whereby services are to be provided only up to a stated amount when it is foreseeable that more extensive services probably will be required, unless the situation is adequately explained to the client. Otherwise, the client might have to bargain for further assistance in the midst of a proceeding or transaction. However, it is proper to deﬁne the extent of services in light of the client’s ability to pay. A lawyer should not exploit a fee arrangement based primarily on hourly charges by using wasteful procedures.
 [No Colorado comment.]
Division of Fee
 A division of fee is a single billing to a client covering the fee of two or more lawyers who are not in the same ﬁrm. A division of fee facilitates association of more than one lawyer in a matter in which neither alone could serve the client as well, and most often is used when the fee is contingent and the division is between a referring lawyer and a trial specialist. Paragraph (d) permits the lawyers to divide a fee either on the basis of the proportion of services they render or if each lawyer assumes responsibility for the representation as a whole. In addition, the client must agree to the arrangement, including the share that each lawyer is to receive, and the agreement must be conﬁrmed in writing. Contingent fee agreements must be in a writing signed by the client and must otherwise comply with paragraph (c) of this Rule. Joint responsibility for the representation entails ﬁnancial and ethical responsibility for the representation as if the lawyers were associated in a partnership. A lawyer should refer a matter only to a lawyer who the referring lawyer reasonably believes is competent to handle the matter. See Rule 1.1.
 Paragraph (d) does not prohibit or regulate division of fees to be received in the future for work done when lawyers were previously associated in a law ﬁrm.
Disputes over Fees
 If a procedure has been established for resolution of fee disputes, such as an arbitration or mediation procedure established by the bar, the lawyer must comply with the procedure when it is mandatory, and, even when it is voluntary, the lawyer should conscientiously consider submitting to it. Law may prescribe a procedure for determining a lawyer’s fee, for example, in representation of an executor or administrator, a class or a person entitled to a reasonable fee as part of the measure of damages. The lawyer entitled to such a fee and a lawyer representing another party concerned with the fee should comply with the prescribed procedure.
Advances of Unearned Fees and Engagement Retainer Fees
 The analysis of when a lawyer may treat advances of unearned fees as property of the lawyer must begin with the principle that the lawyer must hold in trust all fees paid by the client until there is a basis on which to conclude that the lawyer has earned the fee; otherwise the funds must remain in the lawyer’s trust account because they are not the lawyer’s property.
 To make a determination of when an advance fee is earned, the written statement of the basis or rate of the fee, when required by Rule 1.5(b), should include a description of the beneﬁt or service that justiﬁes the lawyer’s earning the fee, the amount of the advance unearned fee, as well as a statement describing when the fee is earned. Whether a lawyer has conferred a sufﬁcient beneﬁt to earn a portion of the advance fee will depend on the circumstances of the particular case. The circumstances under which a fee is earned should be evaluated under an objective standard of reasonableness. Rule 1.5(a).
Rule 1.5(f) Does Not Prohibit Lump-sum Fees or Flat Fees
 Advances of unearned fees, including “lump-sum” fees and “ﬂat fees,” are those funds the client pays for speciﬁed legal services that the lawyer has agreed to perform in the future. Pursuant to Rule 1.15, the lawyer must deposit an advance of unearned fees in the lawyer’s trust account. The funds may be earned only as the lawyer performs speciﬁed legal services or confers beneﬁts on the client as provided for in the written statement of the basis of the fee, if a written statement is required by Rule 1.5(b). See also Restatement (Third) of the Law Governing Lawyers §§ 34, 38 (1998). Rule 1.5(f) does not prevent a lawyer from entering into these types of arrangements.
 For example, the lawyer and client may agree that portions of the advance of unearned fees are deemed earned at the lawyer’s hourly rate and become the lawyer’s property as and when the lawyer provides legal services.
 Alternatively, the lawyer and client may agree to an advance lump-sum or ﬂat fee that will be earned in whole or in part based upon the lawyer’s completion of speciﬁc tasks or the occurrence of speciﬁc events, regardless of the precise amount of the lawyer’s time involved. For instance, in a criminal defense matter, a lawyer and client may agree that the lawyer earns portions of the advance lump-sum or ﬂat fee upon the lawyer’s entry of appearance, initial advisement, review of discovery, preliminary hearing, pretrial conference, disposition hearing, motions hearing, trial, and sentencing. Similarly, in a trusts and estates matter, a lawyer and client may agree that the lawyer earns portions of the lump-sum or ﬂat fee upon client consultation, legal research, completing the initial draft of testamentary documents, further client consultation, and completing the ﬁnal documents.
 The portions of the advance lump sum or ﬂat fee earned as each such event occurs need not be in equal amounts. However, the fees attributed to each event should reﬂect a reasonable estimate of the proportionate value of the legal services the lawyer provides in completing each designated event to the anticipated legal services to be provided on the entire matter. See Rule 1.5(a); Feiger, Collison & Killmer v. Jones, 926 P.2d 1244, 1252-53 (Colo. 1996) (client’s sophistication is relevant factor).
 “[A]n ‘engagement retainer fee’ is a fee paid, apart from any other compensation, to ensure that a lawyer will be available for the client if required. An engagement retainer must be distinguished from a lump-sum fee constituting the entire payment for a lawyer’s service in a matter and from an advance payment from which fees will be subtracted (see § 38, Comment g). A fee is an engagement retainer only if the lawyer is to be additionally compensated for actual work, if any, performed.” Restatement (Third) of the Law Governing Lawyers § 34 Comment e. An engagement retainer fee agreement must comply with Rule 1.5(a), (b), and (g), and should expressly include the amount of the engagement retainer fee, describe the service or beneﬁt that justiﬁes the lawyer’s earning the engagement retainer fee, and state that the engagement retainer fee is earned upon receipt. As deﬁned above, an engagement retainer fee will be earned upon receipt because the lawyer provides an immediate beneﬁt to the client, such as forgoing other business opportunities by making the lawyer’s services available for a given period of time to the exclusion of other clients or potential clients, or by giving priority to the client’s work over other matters.
 Because an engagement retainer fee is earned at the time it is received, it must not be commingled with client property. However, it may be subject to refund to the client in the event of changed circumstances.
 It is unethical for a lawyer to fail to return unearned fees, to charge an excessive fee, or to characterize any lawyer’s fee as nonrefundable. Lawyer’s fees are always subject to refund if either excessive or unearned. If all or some portion of a lawyer’s fee becomes subject to refund, then the amount to be refunded should be paid directly to the client if there is no further legal work to be performed or if the lawyer’s employment is terminated. In the alternative, if there is an ongoing client-lawyer relationship and there is further work to be done, it may be deposited in the lawyer’s trust account, to be withdrawn from the trust account as it is earned.