Social Security 2100 Act This bill modifies the Social Security system, particularly with respect to benefit calculations, fund administration, and beneficiary resources. For example, the bill temporarily increases the primary insurance amount for Social Security benefits for all individuals (from 90% of a certain portion of average indexed monthly earnings to 93%). It also modifies benefit calculations for certain individuals, including by temporarily (1) increasing benefits for widows or widowers in two-income households; and (2) allowing children of a deceased, disabled, or retired worker to remain eligible for benefits through age 25 if they are full-time students. Additionally, the bill temporarily eliminates (1) the government pension offset , which reduces Social Security benefits for spouses, widows, and widowers who also receive government pensions of their own; and (2) the windfall elimination provision , which reduces Social Security benefits for individuals who also receive a pension or disability benefit from an employer that did not withhold Social Security taxes. The bill also modifies the financing and administration of the Social Security trust funds. For example, the bill (1) subjects income over $400,000 to Social Security payroll taxes, and (2) combines the Federal Old-Age and Survivors Insurance Trust Fund and the Federal Disability Insurance Trust Fund into a single Social Security Trust Fund. Finally, the bill establishes requirements relating to Social Security services and resources, including by prohibiting the closure of field offices unless certain conditions are met (e.g., public hearings).