Yes. The Consolidated Appropriations Act, 2021, created a one-year opportunity. Use the prior year’s income if it results in a larger earned income tax credit. But don’t if it results in reducing or barring the credit.
A retirement account to which up to $4,000 (or $5,000 if you are 50 or over) may be contributed for 2007, but deductions for the contribution are restricted if you are covered by a company retirement plan. Earnings accumulate tax free.