There are varying factors that may result in a fare being posted up to 7 days after your trip took place and rarely for a longer TA-determined time period:
Periodic communications outages on transit vehicles: transit authorities have up to 24 hours for fixed fare transactions, or up to 48 hours for variable fare transactions (e.g. fare by distance), to provide and submit the net fare to the bank so that these transactions can be posted to your bank account. In most instances however, approved transactions are posted to your account on the same date as the date of travel.
If your bank account is in a status of non-sufficient funds (NSF) or there is another reason that causes the bank to decline the transit authority's request to authorize payment for travel already permitted, the transit authority will be owed money. The transit authority is permitted to resubmit the request for funds to the bank for up to once per day, and to a maximum of 3 attempts over 7 calendar days after the initial transaction date. If your account is then in good standing and the bank approves one of these transactions, the fare may be posted to your account up to 7 days after the date of your travel.
Tap-to-Pay-Debt - If you owe money to a transit authority because the bank declined an authorization request for payment subsequent to your having been given access to the transit system, the transit authority may at any time that you attempt to enter the transit system execute a process called Tap-to-Pay-Debt (see next FAQ for details) to recover the funds.