Tax services are offered by firms which specialize in filing and preparing taxes. Often these services are provided by accounting firms. Tax firms use their in-depth understanding of complex regulations to offer expertise and guide corporations through the tax process. These services can often save businesses time and money, as well as help ensure legal compliance. Corporations will usually work with firms year-round but will have the most contact in the time leading up to important state and federal tax deadlines. Businesses of all sizes and industries work with these providers and generally assign their accounting departments to coordinate with the firm.