By Jeanne Sahadi, CNN Business

(CNN) -- Even though you can buy things with bitcoin, it's not the same as cash. At least not in the eyes of the IRS.

Virtual currencies are taxed as property, or as an investment, when you sell them. And using them to buy something counts as selling.

If you're paid in bitcoin, for instance, that will be treated as taxable income to you.

That means almost every transaction may be taxable and should be reported.

While bitcoin and other cryptocurrencies may be virtual, they have very real-world tax consequences. If you fail to pay the tax you owe, you will be subject to interest and penalties and, in some circumstances, even criminal prosecution.

So if you couldn't resist getting in on bitcoin's wild ride in 2020 -- it went up about 680% over the past year and has been trading north of $55,000 recently -- let's hope you kept good records, because you are responsible for preserving documentation for every one of your transactions.

So how will the IRS even know I've been using crypto?

In a variety of ways.

There is still no legally required third-party reporting of crypto trades and many types of payments. But any business paying more than $600 to a non-employee or paying wages to an employee must report that income to the IRS, said Mark Luscombe, principal federal tax analyst for Wolters Kluwer Tax & Accounting.

Plus, every federal tax filer at the top of their 1040 form must truthfully answer the question, "At any time during 2020, did you receive, sell, send, exchange, or otherwise acquire any financial interest in any virtual currency?"

But that doesn't mean the IRS will simply rely on an honor system. "They have the perception that there are many more people engaged in virtual currency transactions than is being reported on returns," Luscombe said.

So, together with the US Department of Justice, the tax agency is actively seeking compliance in a few ways.

It has started a "virtual currency compliance campaign" that will include public outreach but also "examinations." That can mean audits.

In addition, the IRS sent letters in the summer of 2019 to 10,000 people alerting them to their tax obligations regarding virtual currencies and urging them to review and amend past returns if they owe back taxes, interest and penalties.

How did it get the names of those 10,000 people? "[T]hrough various ongoing IRS compliance efforts," the agency noted.

One such effort: The IRS is seeking customer lists from cryptocurrency companies through legal summonses.

"The Department of Justice will continue to work with the IRS to ensure that cryptocurrency owners are paying their fair share of taxes," the DOJ said in a statement earlier this month.

How will I be taxed if I sold crypto in 2020?

You must report any capital gain or capital loss from the sale. That will be determined by the difference -- in US dollars -- between how much you paid for your cryptocurrency and how much you received when you sold it.

If you held the investment for less than a year and it had appreciated in value by the time you sold it, your gain will be taxed as ordinary income. If you held it longer than a year, then it would be subject to capital gains tax rates.

If you lost money on the sale, you may use your capital loss to offset any capital gains you incurred in other investments, Luscombe said.

How about if I got paid in a virtual currency for a good or service?

That's reportable as ordinary income to you. And the amount of income reported should be the value in US dollars of the virtual currency the day you received it.

What if I paid someone else in virtual currency?

That's like a sale of bitcoin on which you will realize a gain or loss. The IRS notes that the gain or loss is determined by "the difference between the fair market value of the services you received and your adjusted basis in the virtual currency exchanged."

What should I report if all I did was buy virtual currency in 2020?

You don't have to report it on your 2020 tax return, just as you wouldn't report an investment you purchased and are holding in a brokerage account, unless it threw off taxable income, such as dividends or interest.

If someone gave you a coin as a gift, there will be no tax implications for you until you sell it, so you don't have to report that either.

Will my state tax my crypto transactions?

Probably, but you should see what your state revenue department has said on the issue.

"Most states have not specifically addressed virtual currency, which means that the majority of states that have an income tax would follow the federal lead," Luscombe said.

Any money you earn from your crypto investments or income payments will be factored into your federal adjusted gross income. And most states use your federal AGI as a starting point.

Two states -- Nevada and Wyoming, neither of which have an income tax -- did specify they would not subject virtual currency transactions to the state property tax, Luscombe said.

(For more information on these and other questions, the IRS has created this FAQ. And if your situation is particularly complex, it may pay to see a tax professional with experience in this arena.)