Final answer:
Without specific phase-out rates and maximum EITC amounts for 2019, an exact calculation of Diane's earned income tax credit is not possible. The EITC increases up to a certain income level, remains the same over a certain range, and then slowly decreases to mitigate the poverty trap effect. Specific information about phase-out ranges and maximum credits is required for an exact calculation.
Step-by-step explanation:
The earned income tax credit (EITC) is designed to assist low- to moderate-income working people and to encourage work. In the question, Diane has two qualifying children and earns wages of $18,900 with an additional $900 in dividend income. To calculate Diane's EITC, we must compare her income to phase-out ranges provided for taxpayers with two qualifying children. Diane’s wages are within the phase-out range; therefore, the credit amount will be less than the maximum credit for her situation and must be calculated considering the phase-out rules.
Unfortunately, the exact amount of the EITC cannot be determined from the information provided because the specific phase-out rates and maximum EITC amounts for the tax year in question (2019) were not supplied in the question. However, based on the information regarding phase-out from previous years provided in the question and by understanding the concept of the EITC phase-out, it can be deduced that the EITC is a credit that increases up to a certain income threshold, remains constant for a range of income, and then decreases slowly until it phases out entirely at a higher income level. This structure enables families to avoid the poverty trap where earning marginally more income results in an immediate and significant reduction in government support.