The self-employed contribution isn’t a tax, and treating it like one leads to bad planning

It’s common to hear «I pay a ton of taxes as self-employed» when what’s actually meant is the social security contribution. It isn’t a pedantic distinction: understanding what each thing is changes how you plan your year.

Two payments, two different natures

The RETA contribution is a social security payment, not a tax: it entitles you to benefits (sick leave, retirement, cessation of activity). It’s paid every month from your first day registered, regardless of whether you bill that month, and its amount depends on your real net income declared by bracket — from around €200/month in the lowest bracket to around €590/month in the highest, the result of applying 31.5% to the contribution base chosen within your bracket.

Income tax is a genuine tax, progressive, with brackets that in 2026 run from 19% to 47% at the state level (with regional scales pushing the top marginal rate to 49-54% in some regions). It’s paid on your actual business profit — income minus deductible expenses, including the RETA contribution itself, which is a deductible expense — and it’s settled annually, with quarterly instalments paid on account.

Why this distinction matters for planning

Because the RETA contribution is paid by net-income bracket, you can (and should) review your contribution base throughout the year as your real income changes, instead of leaving it fixed and discovering at tax-return time that you’d been contributing at the wrong bracket for months. Because income tax is progressive and annual, a one-off large payment in a single quarter can push you into a higher marginal bracket for the whole year — something worth planning ahead for if you can split the payment across two tax years without harming the actual transaction.

Invoice withholding isn’t a third tax — it’s an advance on the second one

The 15% withholding (or the reduced 7% during your first two years of activity) that you apply on invoices to other businesses or professionals isn’t an extra payment: it’s an advance towards your annual income tax, deducted from your final bill when you file your return. If your withholdings over the year exceed what you actually owe in income tax, the tax authority refunds the difference. Understanding this avoids the surprise of thinking «I already paid enough» when in reality you only paid in advance.

Planning mistakes that keep repeating

• Keeping a minimum contribution base for years without reviewing it, losing future benefits (retirement, sick leave) by contributing well below real income.
• Not applying the flat-rate discount or start-up reductions out of ignorance, or losing them by missing a minor administrative requirement on time.
• Ignoring quarterly income tax instalments (Modelo 130) and ending up with a much larger final bill than expected on the annual return.

Keep reading on Piratax

• The tax return mistakes Spain’s tax authority catches almost effortlessly
• Living in Spain without becoming a tax resident (and why that line is stricter than you think)
• Monotributo, RESICO, and Spanish autónomo: three very different ways to bill as a freelancer

Sources: current RETA regulations (Social Security), Spanish Income Tax Law and withholding tables for professionals, 2026 brackets. This isn’t tax advice — your optimal contribution base depends on your specific situation and should be reviewed with an accountant.