Employer Tax Contributions

Tax Type	Rate	Base
Social Security (Employer)	6.2%	Up to annual wage base limit ($176,100 for Social Security)
Medicare (Employer)	1.45%	All employee wages (no wage base limit)
Income Tax Withholding	Progressive rates (10% to 37%)	Employee wages (based on W-4)
Business Privilege Tax (BPT)	4% or 5%	Gross proceeds of sales or gross income

Filing & Compliance

• File Form 941 (Employer's Quarterly Federal Tax Return) quarterly for income, Social Security, and Medicare taxes.
• File Form 940 (Employer's Annual Federal Unemployment (FUTA) Tax Return) annually.
• File monthly or quarterly Gross Receipts Tax Returns (Form GRT) by the 20th of the following month.

Guam's income tax system mirrors the federal system, but with its own rates and deductions.

Guam Income Tax

Guam residents are taxed on all income, regardless of source. Non-US citizens or permanent residents are taxed only on Guam-source income. Gross income and deductions are determined using the same rules as the United States. Taxable income includes wages, salaries, commissions, fees, employer-paid expenses, and the fair market value of non-cash benefits like housing or vehicles. Guam's tax rates, similar to US rates, vary based on filing status (single, married filing jointly, head of household).

Federal Taxes

While Guam has its own income tax, residents also pay federal taxes like Social Security and Medicare.

• Social Security Tax: 6.2% of earned income up to a cap of $147,000, resulting in a maximum employee contribution of $9,114 for 2025.
• Medicare Tax: 1.45% of all earned income. An additional 0.9% Medicare tax applies to income exceeding $200,000 for single filers, $250,000 for joint filers, and $125,000 for married filing separately. This results in a 2.35% total Medicare tax rate above these thresholds.

Employer-Sponsored Deductions

Employers in Guam can offer a Section 125 Cafeteria Plan, allowing employees to pay for certain benefits with pre-tax dollars. These benefits include health insurance, dental insurance, supplemental health insurance, group life insurance (up to $50,000 coverage), health savings accounts, dependent care accounts, disability insurance, and flexible spending accounts.

Withholding and Filing

Guam does not use a state withholding form. Employers withhold taxes based on the employee's W-4 form. Employees with multiple jobs should ensure accurate withholding by completing Steps 3 through 4(b) of Form W-4 for their highest-paying job to optimize withholding calculations. For 2025, the tax filing season begins on January 27, 2025. E-filing is available for simple returns. More complex returns, including those with itemized deductions (Schedule A) or business income (Schedule C), require manual filing.

It's important to remember that this information is current as of February 5, 2025, and tax laws and regulations are subject to change. Consulting a tax professional for personalized advice is always recommended.