When it comes to moving large sums of money in and out of your banking and checking accounts, you should keep in mind that Uncle Sam is always lurking in the background, waiting to claim his share of the pie. Whether you have to grease his palm, however, depends on where the money came from. Regardless of the source, however, you'll still have to report it so that the I.R.S. knows to expect your payment.

If you receive — or pay out — more than $10,000 in cash or check in one transaction, the I.R.S. requires you to file Form 8300. File an 8300 for every large transaction including: fees you earn in your line of work, the wedding gift you received from your rich uncle, and cash you pay out to settle a debt or give to the guy who installed your pool.

Who pays? If the money was a gift, the person who gave you the gift is required to pay a gift tax on the money; for you, it's tax-free. However, if you receive the money for providing a service, then you have to pay the piper, and that includes federal and state income tax and Social Security.

And you must report this income on your federal tax return. If the money comes from selling investments — and you sold them at a gain — you'll have to report the capital gain and pay the tax.

If you're moving money from one account to another — say, from savings to checking for the down payment on a house — then a memo on the check or directly on your bank statement will suffice should the IRS ever require further details. It's a good idea to keep a copy of the financial breakdown of your down payment and mortgage debt, along with the bank statements for both accounts, to provide further proof and complete your paper trail.