When Can I Estimate My Tax Deductions?

Having accurate books and records are requirementsexample, ideally the taxpayer would have annual
of all businesses and individuals seeking to take incomemileage logs indicating the destination of the business
tax deductions. However, in reality, businesses andtrips, the business purpose, the individual(s) that were
individuals may not have all the required documentationmet, the date and the number of business miles
and/or receipts to fully support each of theirincurred. This mileage log will substantiate the number
deductions. With this in mind, as professionals we askof business miles that the taxpayer has driven and it
the question - when can a taxpayer estimate taxwill be likely that the IRS would accept this form of
deductions?documentation as support for the taxpayer's mileage
According to the American Institute of Certified Publicdeduction. Moreover, this evidence is crucial to defend
Accountants (AICPA) Professional Standards, "unlessthe deduction during an audit. The lack of the mileage
prohibited by statute or rule, a member may use thelog may cause the reversal of the mileage deduction.
taxpayer's estimates in the preparation of a tax returnFor example, in Tax Court Case Krist v Commissioner,
if it is not practical to obtain exact data and if theTC Memo 2001, the court found that "the taxpayer
member determines that the estimates are reasonablefailed to bring forth any evidence substantiating his
based on facts and circumstances known to theclaimed vehicle expenses. The court also noted that
member. If the taxpayer's estimates are used, theyexpenditures must be documented by means of
should be presented in a manner that does not implyaccount books, diaries, logs or other evidence. Here,
greater accuracy than exists." In other words, anthe taxpayer's lack of any documentary evidence of
estimate should look like an estimate.expenditures prevented the court from approximating
For instance, if a taxpayer estimates business mileageexpenses and ultimately barred their deductibility."
to be 1,000 miles - this looks like an estimate. However,However, if you have incomplete documentary
if the same taxpayer informs you that their businessevidence the IRS may allow mileage deductions under
mileage is 1,125 miles - this appears to be an accuratecertain conditions. Per IRS Publication 463, if you do not
number.have complete records to support a deduction,
The basis of this position by the AICPA Professionalsampling may be an option. Specifically, a taxpayer
Standards is as follows - "accounting requires thecan keep adequate records for a portion of the year,
exercise of professional judgment and, in manysuch as a detailed mileage log, and if the sample is
instances, the use of approximations based onrepresentative of business periods throughout the
judgment. The application of such accountingyear, the IRS most likely will allow your mileage
judgments, as long as not in conflict with the methodsdeduction.
set forth by a taxing authority, is acceptable. TheseWith this in mind, it is clear that estimating tax
judgments are not estimates within the purview of thisdeductions is allowable unless specifically in conflict
statement. For example, a federal income taxwith methods set forth by a taxing authority. However,
regulation provides that if all other conditions forin any case these estimated deductions need to be
accrual are met, the exact amount of income orsupported by evidence to obtain a tax benefit on a
expense need not be known or ascertained at yeartaxpayer's return. In other words, the estimated
end if the amount can be determined with reasonabledeductions that a taxpayer makes need a reasonable
accuracy."basis and supporting evidence to be a valid business
By referring back to the aforementioned mileageexpense.