1. Incomplete Transaction History
As this calculator does not store user data, each standalone calculation depends on a complete transaction history to accurately determine excess distributions and track cost basis and holding periods.
Uploading only the current tax year's activity.
Include all transactions from the very first purchase date up to the current tax year.
2. Illegal Characters & Commas
Special symbols or thousand separators in numeric columns can break the data parsing engine.
Including currency symbols like $ or £, or using commas as separators (e.g., 1,200.50).
Numeric columns (Units & Value) must contain pure numbers only. Use 0 for any empty cells.
3. Unsupported Date Format
Dates must follow a standardized format to be processed correctly across different browser environments.
Using regional formats like MM/DD/YYYY (12/31/2024) or DD/MM/YYYY (31/12/2024).
Strictly use the ISO format: YYYY-MM-DD (e.g., 2024-12-31). See our guide on forcing Excel to ISO date.
4. Positive Units for Dispositions
The calculator identifies share sales (dispositions) by detecting negative values in the Units column.
Using positive numbers for 'Sold' or 'Sale' rows.
Units must be negative (e.g., -100) for all sales to ensure correct FIFO cost basis tracking. See the CSV Standard table.
5. Empty Details or Null Cells
The engine requires data in specific columns to categorize transactions and perform math operations.
Leaving any cell blank in a transaction row, especially the 'Details' column.
The Details column must not be empty. For empty Units or Value cells, always enter 0.
6. Overwriting Original 'Details'
The 'Details' column should mirror original fund transaction descriptions to ensure traceability to broker statements.
Manually rewriting raw descriptions (e.g., changing "Management Fee" to "Ignore") during CSV preparation. This breaks the audit trail and prevents later reconciliation with your broker statements.
Keep the raw description exactly as it appears in your statement (e.g., "Management Fee"). Use the calculator’s Category Mapping step to classify that specific description as "Ignore".
7. Mapping Non-Taxable Events
One of the most common mapping errors involves misclassifying internal fund events that do not constitute taxable distributions or dispositions.
Categorizing non-taxable events such as Management Fees or PIE tax as a "Sale" or "Distribution". This leads to incorrect tax calculations.
These events should be mapped to the Ignore category in our tool to ensure they don't affect the PFIC math. See our guidance on Ignore vs. Purchase/Sale.
8. Reinvestment (DRIP) Mapping Errors
Reinvestment is a dual event—a dividend distribution and a share purchase occurring simultaneously. It is one of the most critical transaction types to map correctly for PFIC compliance.
Mapping a reinvestment solely as a 'Purchase' (missing the taxable distribution) or solely as a 'Distribution' (missing the cost basis update).
Map these transactions as Reinvestment. The calculator automatically splits them into a taxable event and a basis-increasing entry.
Note: Some small, frequent "interest" entries may internaly increase units. These may look like reinvestments but are often internal fund bookkeeping; if they aren't taxable dividends, map them as Ignore.
9. Incorrect "PFIC Start" Date Selection
The PFIC Start Date should be the date you first became subject to U.S. taxation (e.g., obtaining citizenship, a green card, or establishing U.S. tax residency).
Having a holding period that begins before acquiring U.S. taxpayer status, but failing to set the PFIC Start field correctly in the calculator.
Only set a PFIC Start date if the holding period predates your U.S. taxpayer status; otherwise, leave this field at its default.
10. Missing Year-End FMV for MTM
The Mark-to-Market (§1296) method requires an annual valuation update to calculate unrealized gains/losses.
Attempting MTM calculation without providing a 12/31 FMV row for each tax year.
Ensure your CSV has one "FMV" type row for the end of every tax year since the start of the
holding.
See CSV Guide for MTM.