What do you mean by Senior Tax Credit? The Federal Credit for the Elderly or Disabled, or rather some state credit?
To determine if you can claim the credit, you must consider two income limits. The first is the amount of your adjusted gross income (AGI). Adjusted Gross Income (Form 1040 or 1040-SR, line 11). You do not subtract the Standard Deduction (line 12) from that. The second limit is the amount of nontaxable social security and other nontaxable pensions, annuities, or disability income you received.
Looking at the tax form may help, as Gross Income v. AGI v. Taxable Income can get confusing.
2020 Form 1040-SR (irs.gov)
