Investing.com - First-quarter earnings are expected to top those of the fourth-quarter, as companies continue to benefit from the corporate tax rate cut of last 2017.Earnings for the S&P 500 are expected to grow by 17.5% in the quarter, according to Factset. That's up sharply from the 11.4% forecast of December and is the biggest revision since the company started tracking results 15 years ago. Credit Suisse (SIX:CSGN) estimates that the tax cut will add 6.9% to S&P 500 earnings.The financial and tech sectors are expected to lead with earnings growth of 24% and 23%, respectively.In the fourth quarter, a record 77% of companies beat sales estimates. Earnings rose just under 15% during the period. Earnings growth for all of 2018 is forecast at 18.5%.First-quarter earnings kick off in mid-April, with Citigroup (NYSE:C), Wells Fargo (NYSE:WFC) and JPMorgan (NYSE:JPM) all reporting on April 13.