Insider transactions

Open market or private sale of non-derivative or derivative security

• F1 The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $83.9350 to $84.6300, inclusive. The reporting person undertakes to provide to ICF International, Inc., any security holder of ICF International, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote to this Form 4.

Exercise or conversion of derivative security exempted pursuant to Rule 16b-3

• F1 The exercise price for the restricted stock unit exercise was $79.68.

Payment of exercise price or tax liability by delivering or withholding securities incident to the receipt, exercise or vesting of a security issued in accordance with Rule 16b-3

Exercise or conversion of derivative security exempted pursuant to Rule 16b-3

• F1 The exercise price for the restricted stock unit exercise was $79.68.
• F2 Represents the 3rd vesting anniversary (50%) of acquired restricted stock units granted pursuant to the 2018 Omnibus Incentive Plan, as amended.

Open market or private sale of non-derivative or derivative security

• F1 The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted on March 7, 2026. The spouse of the reporting person serves as trustee of the trust.
• F2 The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $89.49 to $89.85, inclusive. The reporting person undertakes to provide to ICF International, Inc., any security holder of ICF International, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote to this Form 4.

Open market or private sale of non-derivative or derivative security

• F1 The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted on March 7, 2026. The spouse of the reporting person serves as trustee of the trust.
• F3 The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $88.44 to $89.42, inclusive. The reporting person undertakes to provide to ICF International, Inc., any security holder of ICF International, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote to this Form 4.

Open market or private sale of non-derivative or derivative security

• F1 The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $88.42 to $88.73, inclusive. The reporting person undertakes to provide to ICF International, Inc., any security holder of ICF International, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote to this Form 4.

Open market or private sale of non-derivative or derivative security

• F1 The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on March 7, 2026.
• F2 The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $80.00 to $80.28, inclusive. The reporting person undertakes to provide to ICF International, Inc., any security holder of ICF International, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote to this Form 4.

Grant, award or other acquisition pursuant to Rule 16b-3(d)

• F1 This award of restricted stock units was granted pursuant to the ICF International, Inc. 2026 Omnibus Incentive Plan, and represents the Reporting Person's annual equity award. These restricted stock units will vest on the one year anniversary of the Date of Grant (July 1).

Grant, award or other acquisition pursuant to Rule 16b-3(d)

• F1 This award of restricted stock units was granted pursuant to the ICF International, Inc. 2026 Omnibus Incentive Plan, and represents the Reporting Person's annual equity award. These restricted stock units will vest on the one year anniversary of the Date of Grant (July 1).

Grant, award or other acquisition pursuant to Rule 16b-3(d)

• F1 This award of restricted stock units was granted pursuant to the ICF International, Inc. 2026 Omnibus Incentive Plan, and represents the Reporting Person's annual equity award. These restricted stock units will vest on the one year anniversary of the Date of Grant (July 1).

Grant, award or other acquisition pursuant to Rule 16b-3(d)

• F1 This award of restricted stock units was granted pursuant to the ICF International, Inc. 2026 Omnibus Incentive Plan, and represents the Reporting Person's annual equity award. These restricted stock units will vest on the one year anniversary of the Date of Grant (July 1).

Grant, award or other acquisition pursuant to Rule 16b-3(d)

• F1 This award of restricted stock units was granted pursuant to the ICF International, Inc. 2026 Omnibus Incentive Plan, and represents the Reporting Person's annual equity award. These restricted stock units will vest on the one year anniversary of the Date of Grant (July 1).

Grant, award or other acquisition pursuant to Rule 16b-3(d)

• F1 This award of restricted stock units was granted pursuant to the ICF International, Inc. 2026 Omnibus Incentive Plan, and represents the Reporting Person's annual equity award. These restricted stock units will vest on the one year anniversary of the Date of Grant (July 1).

Grant, award or other acquisition pursuant to Rule 16b-3(d)

• F1 This award of restricted stock units was granted pursuant to the ICF International, Inc. 2026 Omnibus Incentive Plan, and represents the Reporting Person's annual equity award. These restricted stock units will vest on the one year anniversary of the Date of Grant (July 1).

Grant, award or other acquisition pursuant to Rule 16b-3(d)

• F1 The reporting person is voluntarily reporting the acquisition of shares of the issuer's common stock pursuant to the ICF International, Inc. 2006 Employee Stock Purchase Plan (the ESPP), for the ESPP purchase period of January 2, 2026 through June 30, 2026. This transaction is also exempt pursuant to Rule 16b-3(c).
• F2 The Offering Period (as defined in the ESPP) ended on June 30, 2026, and the shares were acquired on the last business day of the Offering Period.
• F3 In accordance with the ESPP, these shares were purchase at a price not less than ninety-five percent (95%) of the per share fair market value of the Common Shares (as defined in the ESPP) as of June 30, 2026, the last trading day prior to the end of the Offering Period.

Open market or private purchase of non-derivative or derivative security

• F1 Open market purchase of shares in accordance with Issuer's trading policies
• F2 The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $61.45 to $61.65, inclusive. The reporting person undertakes to provide to ICF International, Inc., any security holder of ICF International, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote to this Form 4.

Open market or private purchase of non-derivative or derivative security

• F1 Open market purchase of shares in accordance with Issuer's trading policies

Exercise or conversion of derivative security exempted pursuant to Rule 16b-3

• F1 The exercise price for the restricted stock unit exercise was $65.89.

Exercise or conversion of derivative security exempted pursuant to Rule 16b-3

• F1 The exercise price for the restricted stock unit exercise was $65.89.

Exercise or conversion of derivative security exempted pursuant to Rule 16b-3

• F1 The exercise price for the restricted stock unit exercise was $65.89.

Exercise or conversion of derivative security exempted pursuant to Rule 16b-3

• F1 The exercise price for the restricted stock unit exercise was $65.89.

Payment of exercise price or tax liability by delivering or withholding securities incident to the receipt, exercise or vesting of a security issued in accordance with Rule 16b-3

Payment of exercise price or tax liability by delivering or withholding securities incident to the receipt, exercise or vesting of a security issued in accordance with Rule 16b-3

Payment of exercise price or tax liability by delivering or withholding securities incident to the receipt, exercise or vesting of a security issued in accordance with Rule 16b-3

Payment of exercise price or tax liability by delivering or withholding securities incident to the receipt, exercise or vesting of a security issued in accordance with Rule 16b-3

Grant, award or other acquisition pursuant to Rule 16b-3(d)

• F2 Each restricted stock unit is the economic equivalent of one share of ICF International, Inc.'s Common Stock.
• F3 These acquired restricted stock units were granted pursuant to ICF International, Inc.'s 2018 Omnibus Incentive Plan, as amended. These restricted stock units vest over a period of three (3) years, at 25% on each of the first two anniversaries of the grant and 50% on the third anniversary from the day of grant.

Exercise or conversion of derivative security exempted pursuant to Rule 16b-3

• F1 The exercise price for the restricted stock unit exercise was $65.89.
• F4 Represents the 2nd vesting anniversary (25%) of acquired restricted stock units granted pursuant to the 2018 Omnibus Incentive Plan, as amended.

Exercise or conversion of derivative security exempted pursuant to Rule 16b-3

• F1 The exercise price for the restricted stock unit exercise was $65.89.
• F4 Represents the 2nd vesting anniversary (25%) of acquired restricted stock units granted pursuant to the 2018 Omnibus Incentive Plan, as amended.

Exercise or conversion of derivative security exempted pursuant to Rule 16b-3

• F1 The exercise price for the restricted stock unit exercise was $65.89.
• F5 Represents the 3rd vesting anniversary (50%) of acquired restricted stock units granted pursuant to the 2018 Omnibus Incentive Plan, as amended.

Exercise or conversion of derivative security exempted pursuant to Rule 16b-3

• F1 The exercise price for the restricted stock unit exercise was $65.89.
• F6 Represents the 1st vesting anniversary (25%) of acquired restricted stock units granted pursuant to the 2018 Omnibus Incentive Plan, as amended.

Exercise or conversion of derivative security exempted pursuant to Rule 16b-3

• F1 The exercise price for the restricted stock unit exercise was $65.89.

Exercise or conversion of derivative security exempted pursuant to Rule 16b-3

• F1 The exercise price for the restricted stock unit exercise was $65.89.

Exercise or conversion of derivative security exempted pursuant to Rule 16b-3

• F1 The exercise price for the restricted stock unit exercise was $65.89.

Exercise or conversion of derivative security exempted pursuant to Rule 16b-3

• F1 The exercise price for the restricted stock unit exercise was $65.89.

Payment of exercise price or tax liability by delivering or withholding securities incident to the receipt, exercise or vesting of a security issued in accordance with Rule 16b-3

Payment of exercise price or tax liability by delivering or withholding securities incident to the receipt, exercise or vesting of a security issued in accordance with Rule 16b-3

Payment of exercise price or tax liability by delivering or withholding securities incident to the receipt, exercise or vesting of a security issued in accordance with Rule 16b-3

Payment of exercise price or tax liability by delivering or withholding securities incident to the receipt, exercise or vesting of a security issued in accordance with Rule 16b-3

Grant, award or other acquisition pursuant to Rule 16b-3(d)

• F2 Each restricted stock unit is the economic equivalent of one share of ICF International, Inc.'s Common Stock.
• F3 These acquired restricted stock units were granted pursuant to ICF International, Inc.'s 2018 Omnibus Incentive Plan, as amended. These restricted stock units vest over a period of three (3) years, at 25% on each of the first two anniversaries of the grant and 50% on the third anniversary from the day of grant.

Exercise or conversion of derivative security exempted pursuant to Rule 16b-3

• F1 The exercise price for the restricted stock unit exercise was $65.89.
• F4 Represents the 2nd vesting anniversary (25%) of acquired restricted stock units granted pursuant to the 2018 Omnibus Incentive Plan, as amended.

Exercise or conversion of derivative security exempted pursuant to Rule 16b-3

• F1 The exercise price for the restricted stock unit exercise was $65.89.
• F4 Represents the 2nd vesting anniversary (25%) of acquired restricted stock units granted pursuant to the 2018 Omnibus Incentive Plan, as amended.

Exercise or conversion of derivative security exempted pursuant to Rule 16b-3

• F1 The exercise price for the restricted stock unit exercise was $65.89.
• F5 Represents the third vesting anniversary (50%) of acquired restricted stock units granted pursuant to the 2018 Omnibus Incentive Plan, as amended.

Exercise or conversion of derivative security exempted pursuant to Rule 16b-3

• F1 The exercise price for the restricted stock unit exercise was $65.89.
• F6 Represents the 1st vesting anniversary (25%) of acquired restricted stock units granted pursuant to the 2018 Omnibus Incentive Plan, as amended.

Exercise or conversion of derivative security exempted pursuant to Rule 16b-3

• F1 The exercise price for the restricted stock unit exercise was $65.89.

Exercise or conversion of derivative security exempted pursuant to Rule 16b-3

• F1 The exercise price for the restricted stock unit exercise was $65.89.

Payment of exercise price or tax liability by delivering or withholding securities incident to the receipt, exercise or vesting of a security issued in accordance with Rule 16b-3

Payment of exercise price or tax liability by delivering or withholding securities incident to the receipt, exercise or vesting of a security issued in accordance with Rule 16b-3

Grant, award or other acquisition pursuant to Rule 16b-3(d)

• F2 Each restricted stock unit is the economic equivalent of one share of ICF International, Inc.'s Common Stock.
• F3 These acquired restricted stock units were granted pursuant to ICF International, Inc.'s 2018 Omnibus Incentive Plan, as amended. These restricted stock units vest over a period of three (3) years, at 25% on each of the first two anniversaries of the grant and 50% on the third anniversary from the day of grant.

Exercise or conversion of derivative security exempted pursuant to Rule 16b-3

• F1 The exercise price for the restricted stock unit exercise was $65.89.
• F4 Represents the 2nd vesting anniversary (25%) of acquired restricted stock units granted pursuant to the 2018 Omnibus Incentive Plan, as amended.