A retail installment contract may provide for:
(1) any amount of time price differential permitted under Section 345.055, 345.056, 345.057, or 345.058; or
(2) any rate of time price differential not exceeding a yield permitted under Section 345.055, 345.056, 345.057, or 345.058.
Official text of the Texas Finance Code as published by the Texas Legislative Council.