As CoinTelegraph reports, those who already received letter 6173, titled "Reporting Virtual Currency Transactions" on July 16 now have less than a week to reply to the IRS. The most serious of the trio of letters that were disseminated (sent alongside letters 6174 and 6174-A), 6173 requires immediate action. 

If recipients do not respond to this letter in time, their tax accounts will be audited by the IRS. Recipients are required to respond to this letter within 30 days of the date listed on the letter and requires all crypto transactions between the years of 2013 to 2017 be reported. Reports must include transactions between wallets and exchanges.