http://www.advoco.es/hot-topics/39-do-you-need-to-submit-a-spanish-tax-return.html
Situation 4: I earn less than €22,000 a year
Just as in the UK, Spain has a system of taxation at source which means that a lot of people never fill in a tax return. If you have a salary and some bank interest which have both been taxed at source by your employer and bank respectively, you will already have paid your tax and will usually not have to do a return, provided the combined income does not take you into higher tax rates.
The cut-off point is €22,000 income in the year from employment and pensions, including those from overseas. This limit falls to €11,200 (€12,000 from 2015) under the following circumstances:
- the income has not been taxed at source
- the income comes from more than one source (e.g. two jobs or two pensions, or one of each). If the other sources add up to €1,500 or less you can still use the €22,000 exemption
But a return becomes obligatory in certain circumstances however low your earnings:
- if you have a claim for double taxation
- if you are due a refund
- if you have made pension contributions
- if you are claiming deductions for cost of buying your main residence
- if you have capital gains or income above certain limits (see below)
Remember that it may be in your interest to make a tax return when your earnings are low, for example if you have worked for only part of the year and may therefore be due a rebate because your personal allowances exceed your income from the months you worked.
Note that you will always be required to submit a tax return in your first year of tax residency, however low your income.