Online tools for freelancers, SMEs and accountancy firms
Free calculators and validators for the everyday needs of your business: VAT, net salary, holidays, loans, tax ID, IBAN, the 2027 tax and working calendars and more. No sign-up and no sending your data to any server.
Invoicing and VAT
NIF, DNI, NIE and CIF validator
Checks whether a Spanish tax identification number is correct, calculates the control letter, identifies the type of entity and validates whole lists at once.
Open validator →VAT calculator
Add or remove VAT from any amount at the 21%, 10% and 4% rates, with equivalence surcharge and a breakdown ready for the invoice.
Open calculator →Intra-EU VAT
Find out whether your transaction with the EU carries VAT, the wording for the invoice and the forms to file. Validate VAT numbers.
Open tool →Payroll and labour
Net salary calculator 2026
Convert gross to net using the current Social Security contributions and income tax withholding: per payment, annual, with the full breakdown.
Open calculator →Holiday calculator
Holiday days you are entitled to based on time worked, in calendar or working days, outstanding days and their value in the final settlement.
Calculate holidays →2027 working calendar
2027 national and regional public holidays by region, bridge days, working days and .ics download for Google Calendar or Outlook.
View calendar →Company, banking and deadlines
2027 tax calendar
VAT, income tax, withholdings and corporate tax deadlines filtered by your profile, with download to your calendar.
View deadlines →Company name checker
Checks the name of your future S.L. against the rules of the Central Mercantile Registry before you apply.
Check name →IBAN validator
Checks the control digits of an IBAN, identifies the bank of a Spanish account, converts a CCC to an IBAN and validates whole lists.
Open validator →Loan calculator
Monthly payment, total interest, real APR including the opening fee, and a full amortisation schedule using the French method.
Open calculator →Why these tools
We built them from the questions we get from users of FactuSync and from the accountancy firms we work with. They are the same checks the program runs automatically when you add a customer or issue an invoice with VeriFactu, available here for anyone who needs them.
If you want to see each one in action step by step, read the free tools tutorial on the blog.
They all run directly in your browser: no account needed, no usage limit, and we don't store anything you enter.
The calculators are for guidance only: tax and labour rules change every year and each case is different; for important decisions, confirm with your accountancy firm. We'll keep adding utilities. If you miss one, write to us and we'll consider it.
Frequently asked questions
Are the FactuSync tools really free?
Yes. All the calculators and validators on this page are free, with no sign-up, no usage limit and no paid version. They are a service of FactuSync, the VeriFactu invoicing program for freelancers and SMEs.
Do you store the data I enter?
No. Each tool runs entirely in your browser with JavaScript: the amounts, tax IDs, IBANs or salaries you type are not sent to any server or stored. You can check this by disconnecting from the network after the page has loaded.
Are the results reliable?
The calculations follow current regulations (VAT Law, Workers' Statute, the Tax Agency withholding algorithm, Mercantile Registry regulations, etc.) and are reviewed every year. Even so, they are for guidance only: each case has its particularities, so for decisions with financial impact, confirm with your accountancy firm.
Can I use them on mobile or link to them from my website?
Yes. They are designed for mobile and desktop, and you can link to any of them freely. Several accept URL parameters to preload values, for example /herramientas/calculadora-iva/?base=1000&tipo=21.
How often are they updated?
Each tool shows its last review date. The 2027 calendars will be updated as soon as the BOE and the Tax Agency publish the official versions, and the labour calculators are reviewed with every change to contribution bases or income tax brackets.
Need more than a standalone tool?
FactuSync is a VeriFactu invoicing program for Windows and Mac. Free up to 5 invoices a month, no card and no sign-up.
Download FactuSync