Basically, the way the bill is worded, it allows a taxpayer to claim the full amount in the year that they make the expense, if they have taxable income to cover the full amount. As well, they can roll over that amount for the future 10 years, so the taxpayer can also claim the credit in a future tax year. Those people with lower incomes could claim the credit in a future year if they don't have adequate income in the year they make the expense.
On October 24th, 2017. See this statement in context.