Is it 37% marginal tax rate or 37% effective? I calculated 42% effective on lifetime income, and I suppose the writer was not taxed at 42% on their 100k income

Is it 37% marginal tax rate or 37% effective? I calculated 42% effective on lifetime income, and I suppose the writer was not taxed at 42% on their 100k income from the first years, so the tax rate for later years must have been higher.