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).
If you sold rental real estate via a 1031 exchange you need to keep the tax returns and supporting documents until 4 years after the disposition of the final property in the exchange sequence.