The maximum allowable child and dependent care credit for William and Carla in 2019 is $1,050.
Determine the qualifying expenses:
The total care expenses paid for Carl, their 3-year-old child, amount to $3,500.
Identify the applicable credit limit:
Since they have one qualifying child (Carl), the credit limit for their case is $3,000 (refer to IRS Publication 503 for 2019).
Compare expenses and credit limit:
Since the qualifying expenses ($3,500) are higher than the credit limit ($3,000), the allowable credit amount will be capped at the credit limit.
Calculate the credit based on adjusted gross income (AGI):
In this scenario, Carla's income ($27,500) is considered the AGI because William had no income.
For AGI below $43,000, the child and dependent care credit percentage is 35%.
Therefore, the allowable credit amount is: $3,000 (credit limit) * 35% = $1,050.