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).
By law you must keep certain records for a set period of time. However, it is a good idea to keep records for six years to cover the time limit for bringing any civil legal action against you, including national minimum wage claims and contractual claims.