The best place to download tax forms is the Internal Revenue Service's website. There are many different forms to download regarding taxes.
The Internal Revenue Service keeps track of all tax forms for up to 3 years prior to the current filing year. In certain circumstances, taxes can be filed past that three year mark. Every tax form that can be filed with the IRS can be located on their website and can be printed out or downloaded for personal use. However, an accountant or an accounting agency may have these tax forms available. Some accounting agencies, such as H&R Block, have the option of downloading back tax forms for a fee.
When downloading previous tax year forms from the IRS's website, all the forms are in a PDF document. These documents are read-and-write documents, so that as soon as the form is opened in the browser, information can be entered in the blocks provided as necessary. Then the document can be saved or printed out once completed. However, like any other tax form, this can require additional steps such as a signature or sending the form to a specific office for back filing. It is always best to contact the IRS or another tax official for information or guidance on this.