Complex sentence: In the United States, the taxpayer commonly applies for the loan through a paid tax preparation firm, which receives a fee for each loan originated, but in the United States the Internal Revenue Service rules prohibit basing this fee on the amount of the expected refund.
Split into simpler sentences: In the United States, the taxpayer commonly applies for the loan through a paid tax preparation firm. The tax preparation firm receives a fee for each loan originated, but in the United States the Internal Revenue Service rules prohibit basing this fee on the amount of the expected refund.