Why Spanish people have two surnames (and who picks the order)
Two surnames, one from each parent, kept for life even after marriage: Spaniards take it for granted, but it’s a rather unusual custom.
One from each parent
In Spain everyone has two surnames: the first surname of one parent and the first surname of the other. So each generation keeps one surname from each side, and today’s second surname is usually the one that disappears in the next generation.
The custom is old, but it became law with the Civil Registry in the late 19th century: since then both surnames are compulsory and appear on every official document.
Marriage changes nothing
Unlike in many countries, nobody in Spain changes surnames on marrying. A married woman is still called exactly what her birth certificate says.
That’s what makes Spanish family trees so rich: every person carries two clues, and women don’t lose theirs in the records.
Who goes first: 1999 and 2017
For a long time the father’s surname always came first. In 1999 the law let parents put the mother’s first if both agreed. And since 30 June 2017, under the 2011 Civil Registry Act, there’s no default at all: parents choose the order, and if they can’t agree the registrar decides in the child’s interest.
The order chosen for the first child applies to all their siblings. And at 18, anyone may ask to swap their own two surnames.
This matters when counting your surnames: in a branch with the order swapped, the list follows the mother’s surname. In the app, just use “Swap order” on that person.
Other countries, other rules
Most Spanish-speaking countries in the Americas follow the same system as Spain. Portugal and Brazil also use several surnames, but usually the other way round: the mother’s first and the father’s last, and the last one is passed on.
In English-speaking countries the norm is a single surname, the father’s, with one spouse often taking the other’s on marriage. So in an English or American tree each generation leaves only one surname per person.
Every surname in your tree
Follow the Spanish system generation after generation and your two surnames become 4, 8, 16… A Thousand Surnames works them all out from your tree, in order, and tells you how common or rare each one is in Spain.