I’m self-employed and use the M&IE standard federal per diem rates for meal costs while away from home. If I take a customer to lunch, can I base my deduction on the actual cost of that meal?

Estimated tax

Advance payment of current tax liability based either on wage withholdings or installment payments of your estimated tax liability. To avoid penalties, you generally must pay to the IRS either 90% of your final tax liability, or either 100% or 110% of the prior year’s tax liability, depending on your adjusted gross income.