Hello autónomo friends, here we are at the end of August. The end of our long summer break without income, but full of beaches, cervezas, tinto de verano, seafood and ice cream. (Or just crashing in your childhood bedroom.) My summer involved watching horse races on the beach in Sanlúcar de Barrameda in Cádiz, a very unique experience, as well as a tour around Granada, Estepona, Cádiz city, and the beaches between El Rompido and Punta Umbría (Huelva). I already miss those long relaxing days!

Summer daydreaming aside, if you’ve done the baja to give yourself a break from those hefty social security payments, great! But what happens when you’re ready to start working again? I’ve got you covered. 

Just like you had to do the baja for both Hacienda and Social Security, you’ll need to do both steps to darte de alta. It’s important to do both steps on the same day, and preferably Hacienda first. Seguridad Social confirms your tax registration data to complete the process.

Steps to reregister for autónomos after summer with Hacienda

Start by going to the Hacienda website. It’s exactly the same webpage and form you used to do the baja, or any modification – everything is done in Modelo 036. As usual, choose Modelo 036. Cumplimentación y presentación telemática. Fun fact: Hacienda eliminated Modelo 037 early in 2025, it was a simpler version of 036.

El Modelo 037, una declaración censal simplificada para autónomos y pequeñas empresas, ha sido eliminado oficialmente desde el 3 de febrero de 2025.

To log in, choose Cl@ve Móvil or Certificado Electrónico. 

A little surprise – it will ask you if you want to do a simplified version ¿Quiere acceder a un Modelo 036 simplificado? To which we can say Sí, because more than likely your situation will not be that complicated. When in doubt, just say No and do the full version. The form will appear and you can start filling it in.

101 – Check that your name and NIE are correct.

A) 111 – Check “Alta en el censo de empresarios, profesionales y retenedores.”

Skip B and C, and go to the bottom. In Lugar, fill our your city name and today’s date. (Remember you need to do the alta before you start working again or up to two days after.)

For Firma en calidad de, select Interesado. To sign the form, fill in your full name.

It looks like you’re already done, but not yet. Go back to the top of the page where you’ll see tabs for the different pages. Open Page 2A and fill out section A, Personas Físicas:

A8 – Nombre comercial, put your name or your business name if it’s different.

You can most likely skip A9 if you’re not registering as a Emprendedor de Responsabilidad Limitada (this involves more paperwork and registrations – literally, “Pero antes, debes firmar la escritura ante notario y haberla entregado en el Registro Mercantil.” If you haven’t done this then definitely skip A9 and A10). 

You can probably also skip A90, that’s a field for non-residents of Spain. This gives non-residents a special tax code. 

In either A27 or A38 you can include your business website address. No idea why there are two fields for this!

In the next section you can choose to enter your phone number and email to get electronic notifications. I always sign up for all of them (“Alta”) because when we did the Baja, we canceled all of this. 

Then you’ll fill in all your address details. If you select Buscar Dirección, it will help you get the address fields correct. Once those fields populate, don’t forget to fill in the rest. In my case, I fill in Tipo Num, Num Casa, Planta and Puerta. Don’t forget the final field in this section. Referencia Catastral. When you did the Alta for the very first time, you should have filled this in, so maybe you saved the number somewhere. (Handy tip: look for the PDF copy of your first Alta and if your address is the same, you can copy and paste the Catastral number in.) If you don’t have it, just click the link to open a new page and look up your address and you’ll can copy and paste the long Catastral number. Don’t forget A39! If you have a Referencia Catastral, choose 1, if not choose 4.

The next section is only if you have a different address you want to use for notifications. Normally this is not the case.

Go back to the top and open Page 4. (Why is there no Page 3?) Here you’ll add your work activity. 

Click Añadir Registro, which will open a new section. You can’t actually enter your Código IAE directly, you need to use Buscador de Actividades. I always type 933 in the search box and scroll down to 933.9, Otras Actividades de Enseñanza (language teaching is included here). Select your IAE code and it will auto-populate the form. 

Now you get to decide – are you working from home in a dedicated office? You can choose “La actividad se desarrolla fuera de un local determinado” if you teach in different places, or if you don’t want to declare your home office. I usually choose this option because I work online from my living room, which technically doesn’t count as a dedicated workspace, so I choose not to declare it. If you choose “La actividad se desarrolla en un local determinado (locales directamente afectos a la actividad)” you can deduct a percentage of your rent and utilities on your taxes. My rent is cheap for now so I don’t worry about this.

Whichever you choose, click Añadir Registro in that section. Choose Alta and fill in the date, then the city details and click Guardar. Then click Guardar at the bottom of the window. (You can add other work activities if you have different types of projects like translating or web design). 

Let’s move on to Page 5.

Section A is important for teachers: ¿Realiza exclusivamente operaciones no sujetas o exentas que no obligan a presentar autoliquidación periódica? This asks if we are exempt from paying IVA, which YES, we are! (Until someone tells me otherwise.) So if you’re a teacher, click Sí, otherwise click No. (Fun story: one year I clicked No and filled in all the other sections and Hacienda got mad at me for not paying IVA for several months. Oops!) If you do have to declare and pay IVA, definitely get some other help filling in these sections to make sure you’re doing it right. I don’t want to guide you in the wrong direction.

If you’ve clicked Sí, you can skip sections B, C and E. (Someone really needs to teach Hacienda proper counting and letter order.) 

We can move on to Page 6, for the IRPF.

Here’s an important consideration: do you include retenciones (withholdings) on your invoices each month? Technically, if at least 70% of your income includes these retenciones, you don’t have to pay the quarterly IRPF tax. 

Los que desarrollan actividades agrícolas, ganaderas, forestales y los profesionales, no están obligados a efectuar pagos fraccionados si en el año natural anterior al menos el 70 % de los ingresos de su actividad fueron objeto de retención o ingreso a cuenta.

When I started as autónoma over seven years ago, I was working for an American company, so I wasn’t including retenciones. I got used to paying IRPF every quarter. So out of habit, I just choose to say “Yes, I need to do pagos fraccionados” even though for the last five years I don’t need to do this. My quarterly tax payments are usually very low or nonexistent, and I always get a big refund the next year, so it doesn’t bother me to continue doing this. Since I’ve spent the first half of 2025 declaring IRPF, I’m going to do the Alta for this again, just to not get any scary notifications from Hacienda asking where my IRPF is. (I’ll probably do a Modificación for January 2026.)

So if you DO decide or need to do IRPF, fill in 600 (Alta) and 602 (date). Then go on to 609 (Inclusión) and 650 (date) if you earn less than 600.000 euros a year (umm, all of us?!). Estimación directa simplificada,si facturas menos de 600.000 € al año.

You can most likely skip those next two long sections 1) and 2). 

If the number is correct click Continuar. 

Next, when it asks you ¿En qué organismo declaras el Impuesto de Actividades Económicas (IAE)?, choose Agencia Tributaria in most cases, unless you’re in the Basque Country and know you belong to a different tax organization. Below that add your IAE code from Hacienda (language teachers: 9339.) You may get a little warning that it couldn’t be found. It’s fine though, probably because you just did the Alta, the system hasn’t had time to update and they’ll check again later. Just click Continuar.

Unless you’re part of a “colegiado” profession like doctors, psychologists, or lawyers, you can click No es mi caso.

Next, fill in your address. With the next popup about additional activities, click Continuar.

Then you’ll get a nice explanation about the monthly payment, give it a quick read and click Entendido, continuar.

Here’s a fun section! Estimating your monthly income! Well, you should already know more or less how much you earn (net) each month, if not there are some helpful links to help you calculate. Once you’ve calculated and moved to the next section, you’ll be asked to move the slider to the Base de Cotización that you want to use to calculate your payment. I usually match the slider as close as possible to the lowest number in Tramo de bases de cotización (the blue box). Continue when you’ve chosen the number you want.

You’ll get a notice saying you don’t qualify for “bonificaciones.” Those are usually for people with special circumstances. So click Continuar.

Then you’ll need to answer whether you work por cuenta ajena (for a company with a contract) in addition to being autónomo. If not, click No es mi caso. 

You get to choose from a list of mutuas – insurance providers in the case of needing to request sick leave. Not sure why but I always click Fremap. 

Now comes the fun popup window telling you how much you *get* to pay to Seguridad Social each month! It should be somewhere around 300 euros a month, but it all depends on your projected income. If you disagree with this amount, at the bottom click Volver and you can move the slider to recalculate.

On the next page you’ll see your phone number and email that they handily have saved for you, edit them if necessary. They’ll send you an 8-digit code via SMS to confirm. 

Then you can either confirm your bank account details if they’re correct from before, or enter new ones. 

On the last page you have a chance to double check and modify your data. Click the little box at the end to give your consent. Then click Firmar y Solicitar Alta.

When it’s done processing, be sure to download a copy of the documentation (a ZIP file). 

You’re all done for this school year! Until next year’s baja at least. Treat yourself to a cold beverage, you deserve it, and enjoy your last days of summer!

PS: Need some help getting organized? I’ve created a free autónomo kit with some helpful spreadsheets to organize your time, invoices, clients/students, and budget.