Otherwise, you'll save more tax dollars by foregoing the home mortgage interest deduction and claiming the standard deduction instead. Complete Schedule A and compare the total of your itemized deductions to your standard deduction to find out which method is most advantageous for you.
How long a patent lasts depends on the type of patent being issued and the country issuing the patent. For example, under recent changes in the laws, in the United States, patents are now granted for a term of 20 years from the date of application (14 years for design patents).
In the case of employment records, the IRS guidelines say to keep the records for a minimum of  four years after you pay the tax or the tax is due, whichever of the two dates is later. Small business expert Rieva Lesonsky suggests you keep employment records for a minimum of two years and for up to seven years. She says that most states have a two-year statute of limitations on lawsuit filings by former employees, so you want to make sure you have documents at hand if this occurs.