Accounting Assistant at Mandex, Inc. – Fairfax, Virginia

Req ID: 171

Job Title: Accounting Assistant

Location: Mandex Corporate Fairfax, VA, US 22033

Organization Unity: CORP HQ

Date Opened: 3/11/2026

Job Type:

Full-time

Category:

Finance

Education:

Associate Degree

Travel:

0 - 10%

Description:

Accounting Assistant

Fairfax, VA (HQ)

On-site

Salary Range: $24.50-$26.00 per hour

MANDEX currently has a need for a full-time Accounting Assistant to join our team at our Headquarters Office in Fairfax, VA. The Assistant will participate in the maintenance of day-to-day accounting and payroll operations and support our Headquarters personnel. This is a non-exempt position.

Your future duties and responsibilities:

• Processing accounts payable for vendor purchases, utilities, electronic employee expense reports, check requests, etc., and corresponding with vendors and employees.
• Preparing and filing for 401(k) contributions, match and loans to Principal.
• Assisting with monthly reports, data entry, and filing.
• Inputting timesheet entries for wage determination payments, leave payouts, and other entries.
• Running AP checks and mailing out checks.
• Assisting with W2s and 1099s at year end.
• Assisting with payroll functions such as processing payroll timesheet entries semi-monthly, creating the bank payroll payment file as well as payroll related taxes.
• Reviewing and processing monthly invoices.
• Setting up project numbers for new tasks in Deltek CostPoint.
• Reviewing for accuracy paperwork submitted to the corporate office prior to processing and returning incorrect data for completion.
• Providing other clerical assistance to Corporate and field offices as needed.

Required qualifications to be successful in this role:

Experience:

• Excellent verbal and written communication skills.
• Excellent interpersonal skills with the ability to manage sensitive and confidential situations with tact, professionalism, and diplomacy.
• Excellent organizational skills and attention to detail.
• Proficiency with Microsoft Office Suite and related software.
• Proficiency with or the ability to quickly learn payroll management, and similar computer applications.
• Prior working experience with Deltek CostPoint accounts payable, electronic employee expense report and the payroll modules.
• Minimum of 1 - 3 years of Payroll/ Administrative office experience. Government contractor experience preferred.

Education:

• Highschool degree
• Associates and or bachelor's degree preferred in Accounting, Human Resources, or a related field

Security Level:

None

Other Requirements:

Must be a U.S. Citizen.

What you can expect from us:

MANDEX, Inc has over 50 years of experience in all facets of information technology including systems engineering; systems testing; systems design and implementation; cybersecurity and information assurance; electronic and physical security; as well as logistics and warehousing.

MANDEX, Inc. is a collaborative, mission-driven organization where professional advancement, supportive leadership, and an inclusive culture are the core of everything we do! Come work with us!

Benefits we offer:

• Health insurance
• Vision insurance
• Dental insurance
• Paid time off
• Tuition reimbursement
• Employee assistance program
• Short-term disability
• Long-term disability
• Health savings account
• Flexible spending accounts
• Basic Life & Disability insurances
• Voluntary AD&D Insurance
• Voluntary Accident Insurance
• Voluntary Critical Illness Insurance
• 401(k) Retirement Plan (MANDEX, Inc offer pre-tax and post-tax Roth contributions, and match 100% of the first 6% elected contribution)

Additional Information

• Interview Round 1
• Interview Round 2
• Background Checks & Drug Screening
• Offer Letter
• Your NEXT big challenge begins

MANDEX, Inc. is an Equal Employment Opportunity employer and does not discriminate on the basis of race, national origin, gender, sexual orientation, disability, veterans’ status, age, or other legally protected status.

MANDEX Inc. reserves the right to perform background screening and drug testing prior to extending offers of employment.

MANDEX attracts and retains smart and motivated professionals in the government contracting industry. We offer competitive salaries and excellent benefits packages, including a matched 401(k) plan.