If a self-employed worker changes relevant details of their business, the usual way to report this to the tax authorities is the census amendment return, normally through Form 036. But that does not always cover every obligation: if the change also affects the RETA registration status, you must also consider notifying Social Security.
The short answer to the main question is this: a change must be reported with Form 036 when it alters the census data registered with the Tax Agency, and it must also be notified to RETA when it changes details that Social Security manages under the self-employed regime. It is worth checking each case carefully, because forms, deadlines, and criteria can change over time.
Which changes require updating the tax census
The Tax Agency states that, if you have already filed your census registration, any variation in the data included in that return or in any later return must be reported through an amendment return. In practice, this affects the details that identify your activity and other census elements that remain in force while you work as self-employed. Form 036 is the general form for registration, amendment, and deregistration in the census of businesses, professionals, and withholding agents. [1][3] [1] [3]
Among the changes that may require a census amendment are address, activities and premises, representatives, and certain details linked to VAT, personal income tax, Corporate Income Tax, and withholding taxes. The Tax Agency itself offers a service within its website for consulting and amending census data, which makes it easier to check which sections can be updated without redoing the entire registration. Before filing anything, it is advisable to identify exactly which detail has changed and whether it affects the census. [2][8] [2] [8]
- Changes to the tax address or notification address.
- Registration, deregistration, or alteration of activities and premises.
- Changes to representatives or certain tax details.
- Changes affecting census options or waivers already declared.
How to use Form 036 in practice
Form 036 is the full census return for registration, amendment, and deregistration. The AEAT treats it as the reference form for reporting census data when the self-employed worker needs to update information already declared. The online office provides a census data consultation and amendment service, a useful access point for checking which options are available and which information is still active in your file. [2][3] [2] [3]
In a well-planned filing, the practical order is usually straightforward: first identify the change, then check whether it falls within the tax census, and finally submit the relevant amendment. Not every change requires the same section or repeating all the registration details, but it is important not to leave out any variation that affects the declared tax situation. If in doubt, checking the AEAT online office in advance helps avoid inconsistencies between forms. [2][8] [2] [8]
- Identify the detail that has changed before starting the process.
- Check whether the change belongs in census data or another procedure.
- Use the AEAT online office to consult or update the information.
- Keep the filing receipt once the change has been submitted.
When you must also notify Social Security
Social Security reminds us that the self-employed worker is responsible for requesting registration, deregistration, and data changes in RETA. In other words, updating the information with the tax authorities is not enough if the change also affects the self-employed scheme. In addition, the general deadline for a RETA data change is 3 calendar days, according to official Social Security information. [4][5] [4] [5]
That is why, whenever a change arises, it is useful to separate two questions: one tax-related and one related to Social Security. If the amended detail only affects the AEAT census, the procedure stops there. If it also alters the RETA status, it must be reported to both administrations. Official Social Security information allows these procedures to be completed online through its office, using a digital certificate or Cl@ve, depending on the case. [4][6] [4] [6]
- A tax census amendment does not always replace the RETA notification.
- The self-employed worker must check whether the change affects Social Security status.
- RETA data changes have their own general deadline.
- The procedure can be completed online at the Social Security Office.
Useful differences between tax changes and RETA changes
The main difference lies in who manages each piece of data. The tax authorities handle the tax census: activity, address, premises, tax options, and other elements linked to the tax relationship. Social Security, by contrast, manages the self-employed worker’s classification in RETA and the changes that affect that affiliation. For that reason, the same change can have two different effects and require two separate notifications. [2][4] [2] [4]
A practical example is a self-employed worker who changes their workplace premises: that detail may require a census amendment if it is part of the information declared to the AEAT. However, not every move automatically implies a RETA variation; it will depend on how it affects the worker’s Social Security status. In any case, the best approach is to review both sides before considering the procedure complete. [2][4] [2] [4]
- The tax authorities focus on the census and tax status.
- Social Security focuses on affiliation and the self-employed worker’s data changes.
- The same event may affect only one administration or both.
- It is not wise to assume that a tax filing automatically resolves RETA too.
Recommended steps before filing the amendment
Before filing anything, it is useful to follow a basic sequence: first, identify the specific change; second, check whether it affects the AEAT census; third, review whether it also changes the RETA status; and fourth, keep the receipts for both procedures when applicable. This approach reduces mistakes and helps keep both administrations consistent. [1][4][8] [1] [4]
It is also worth remembering that the rules and online office may be updated. The BOE publishes Order EHA/1274/2007, which approves Forms 036 and 037, with the current consolidated text and later amendments. Even so, forms, deadlines, and filing criteria can change, so before filing it is sensible to check the latest official information from the AEAT and Social Security. [7] [7]
- Step 1: define exactly which detail has changed.
- Step 2: check whether it affects the AEAT census.
- Step 3: review whether it must also be reported in RETA.
- Step 4: keep the receipt and verify the current version of the procedure.
Frequently asked questions
When must a self-employed worker file Form 036 to amend their details?
It must be filed when any detail included in the census return already submitted, or in a later return, changes. The AEAT states that those variations must be reported through an amendment return. Depending on the case, this includes address, activity, premises, representatives, or other tax details.
Is a change at the tax office enough to update everything for the self-employed worker?
Not always. Form 036 serves for the Tax Agency census, but Social Security manages RETA separately. If the change also affects affiliation or data changes in the self-employed scheme, it must also be reported to Social Security.
What is the deadline for reporting RETA changes?
Social Security states a general deadline of 3 calendar days for data changes in the Self-Employed Scheme. Even so, it is advisable to always check the current information before filing, because deadlines and procedures may be updated.