As previously discussed, the tax year in Israel runs from 1 January to 31 December, i.e. concurrent with the calendar year.
Tax returns cover the year in question, and obviously cannot be filed until the start of the next year.
The tax return itself is just three pages long, and contains - apart from identifying information - all of your income, claims to deductions and credits and tax deducted at source.
Each field is given a three-digit code and these often appear on supporting documentation.
In the vast majority of cases, the tax return must be filed electronically, either via the Internet or directly onto the tax computer by an agent. To file on the internet: www.misim.gov.il/sh1301 (requires registration).
However, the electronic filing is only the first stage - you also need to physically sign on the tax return, attach appendixes and other supporting documentation and hand the return into a tax office. Only then is the tax return considered filed.
Supporting documentation will include profit and loss accounts, forms 106 (summary of salaries), summaries of amounts paid into various insurances, receipts of donations made etc.
You should always take a copy of what you file, it has been known to happen that papers get lost in the tax offices!
The law requires you to file your tax return by 30 April (if not filing electronically) or 31 May (for electronic filing) following the end of the tax year. However in many years these dates are extended by a month as it is difficult to get all the necessary paperwork in time (this has happened for 2012 ).
That being said, there are arrangements with accountants whereby, provided that the accountant meets certain criteria (percentage of their clients' returns filed by given dates), their remaining (eligible) clients will automatically get filing extensions to 31 August and 30 November. It is possible to get an extension beyond this date, but this will be at the discretion of the tax office.
Filing your tax return late has two main implications - hefty fines (over NIS 1,000 for each month late) and, perhaps more importantly, no possibility of extensions in the next two years, even if the accountant meets their target.
Finally, a note of caution. Although the filing deadlines are reasonably generous, interest and linkage (הצמדה) accrues on your tax balance from 1 January (i.e. the day after the tax year ends), regardless of when you file your return.