Reduction of gene flow. However, speciation might also happen in a population with no specific extrinsic barrier to gene flow. Imagine a situation in which a population extends over a broad geographic range, and mating throughout the population is not random.
The Internal Revenue Service places restrictions on how far back you can amend your tax return, regardless of whether you owed tax or received a refund. Filers must use Form 1040X to amend a return and should only file an amendment to report certain changes. You have three years from the due date of the original return or two years from when you paid tax owing to submit an amended return. A pen next to an income tax form.
However, in the long run, taxes may be less certain. With some debts, such as medical bills or credit card debt, the statute of limitations can cut off a creditor who might try to sue you over an old debt. How far back the IRS can go to collect back taxes depends on your circumstances. Federal law sets limits, known as collection statute expiration dates, on how long the IRS can collect back taxes from taxpayers. After the expiration date passes, the IRS can't try to make you pay your old taxes.