What Is the Additional Number in the Saudi National Address and Why It Matters

You open your company profile in your accounting system, or the registration form on the Fatoora portal, and there it is: a field called Additional Number. Four digits. No explanation of where it comes from, and no answer to the question that actually matters, which is whether leaving it blank will break your invoices.

Short answer: the additional number is a genuine component of the Saudi National Address, issued by Saudi Post (SPL), and it pins your building to a precise point on the map. The longer answer concerns its role in e-invoicing, and that is where most published guidance gets it wrong.

This guide builds the full picture from primary sources: what the additional number is, what Saudi Post officially calls it, how it differs from the building number and the unit number, where it sits inside the invoice XML, and what the published ZATCA validation rules actually say about whether it is mandatory.

What is the additional number in the Saudi National Address?

The additional number is a 4-digit number assigned by Saudi Post to each building in the Kingdom, and it represents the precise location coordinates of that building. Its job is to identify a building when the street or district name is not enough to find it, which is common in newer developments where streets have not been named yet.

A complete National Address has six official components: building number, street, additional number, district, postal code, and city. Each answers a different question. The building number answers “which building on this street?” The additional number answers “where exactly does this building sit on the map?”

Taken together, the building number, additional number, and postal code produce a single point that does not repeat anywhere in Saudi Arabia.

Why you will not find “additional number” on the Saudi Post website

This deserves a pause, because it is the root of most of the confusion. Open the official National Address page on the Saudi Post website and search for “Additional Number.” You will not find it. The official term is Secondary Number, which Saudi Post defines as “4 numbers representing the accurate location coordinates; beneficial when there’s no street or district names.”

So what happened? “Additional number” is the name that settled into everyday use, and it appears across registration forms and government channels, while “secondary number” remained the formal term in the addressing documentation. Two names, one number.

That naming gap has a practical consequence. A lot of published guidance describes the additional number as identifying “the exact unit, apartment, or office within the building.” That describes the unit number, not the additional number. The additional number locates the building itself on the map, not anything inside it.

Why the additional number was created

Before the National Address system, Saudi Arabia relied on PO boxes plus a hand-written description of the location. A PO box tells you the postal district and nothing about where a building physically stands. Delivery drivers worked from directions like “past the second traffic light, next to the bakery.” That works for a small city with light shipping volume. It does not work for e-commerce at national scale.

The National Address solved it differently: every building gets a standard machine-readable identifier. The result is an address any party can verify automatically, government or private, instead of depending on a human description.

The additional number is the part that carries the geographic precision. Street names can repeat across districts, and a building number is tied to the street it sits on. Coordinates do not repeat. That is why the additional number matters most in new developments whose streets have not been named, which is exactly the case Saudi Post calls out in its own definition.

Additional number vs building number, unit number, and postal code

Four numbers appear on the same form, and it is easy to put one in the wrong box. Here is the separation:

Note that the additional number is not your tax registration number, which is a 15-digit identifier issued by the Zakat, Tax and Customs Authority for an entirely different purpose. If you need that one, our guide to the tax ID in Saudi Arabia covers registration end to end.

Where the additional number appears in the e-invoice

The Zakat, Tax and Customs Authority builds the e-invoice on the UBL 2.1 standard. Seller and buyer addresses are both carried inside a <cac:PostalAddress> block, and each National Address component maps to its own tag.

The additional number is carried specifically in <cbc:PlotIdentification>. That tag name is another source of confusion, because it looks nothing like “additional number.” Anyone reading the XML for the first time tends to skip past it.

If you are implementing the integration yourself rather than using a certified provider, our walkthrough of technical integration with ZATCA FATOORA covers the surrounding onboarding steps.

Will your invoice be rejected if the additional number is empty?

Here our answer differs from most of what is published, and it rests on the validation rules shipped in the authority’s own e-invoicing developer toolkit rather than on general impression.

The rule governing the seller address is BR-KSA-09. Its written message states that the seller address must contain street name, building number, postal code, city, district, and country code. The additional number is not in that list.

More to the point, the condition the rule actually evaluates checks for six elements only: street name, building number, city, postal code, district, and country code. Leaving the additional number empty does not fail the invoice under this rule. The rule is also classified as a warning rather than a hard error.

The buyer address is governed by BR-KSA-10, and its requirement is narrower still: street, city, and country code. It also does not apply at all to simplified tax invoices and their associated credit and debit notes. In other words, a simplified tax invoice issued to an individual does not ask you for buyer address data.

So what is the practical takeaway? Always fill in the additional number, but for the right reasons: it is part of your officially registered National Address, carriers depend on it, and the rule text itself lists it among address data. Just do not build your expectations around it being the reason invoices get rejected. Address-related rejections usually trace back to a missing district, postal code, or building number, which are the fields the condition genuinely checks.

This distinction is not academic. Someone who assumes the additional number is the culprit spends their time on a healthy field while the real error sits in another one they never looked at. For the wider list of rejection causes, see our breakdown of e-invoice rejection errors in ZATCA Phase 2.

How to find your additional number step by step

Issuing it is free and does not take long. The only trustworthy source is the Saudi Post National Address platform, not Google Maps and not unofficial apps.

1. Open the National Address platform at splonline.com.sa, or download the National Address app.
2. Sign in through the National Single Sign-On using the same credentials as Absher.
3. Choose to issue a National Address, then select the beneficiary type: individual or business.
4. Pin the building location accurately on the map. The system derives the building number and additional number from the coordinates of the point you set.
5. Review all six fields before saving: building number, additional number, street, district, postal code, city.
6. Save the address certificate as a PDF. You will need it when issuing a commercial registration and opening your entity file with government bodies.

For businesses, the process runs through Absher Business or the Balady platform, and the National Address is linked to the commercial registration and to your file with the authority. Any later change, such as moving to a new premises, must be updated in three places: Saudi Post, the commercial registration, and your VAT file.

Additional number in Riyadh, Jeddah, and Dammam

Many people search for “additional number Riyadh” or “additional number Jeddah,” so one idea needs correcting: there is no single additional number for an entire city. The additional number belongs to one specific building, and it differs from one building to the next even on the same street.

What varies at city level is the postal code, which is a different component altogether. Postal code ranges are distributed geographically: Riyadh generally starts at 11 and upward, Jeddah at 21 and upward, and the Eastern Province at 31 and upward. Conflating a postal code range with the additional number is common in published content, and it leaves readers thinking they can somehow derive their additional number from their city. They cannot.

The only way to get it is to issue the National Address for your specific building through the Saudi Post platform, whatever your city.

A practical diagnosis: an invoice rejected over its address

Take a real case. You run a specialty coffee roastery in Al Yasmin, Riyadh. You completed registration, received your cryptographic stamp identifier, and issued your first tax invoice to a business customer. The response comes back with a warning about the seller address.

The first instinct is to open the additional number field and check it. That is usually not where the problem is. Order your checks the way the system actually checks them:

1. District. The single most commonly empty field, because people assume the city is enough. District is a separate, checked element.
2. Postal code. Confirm it is a full 5 digits, and that it is your building’s code rather than a generic city code.
3. Building number. Four digits, copied from the address certificate rather than from memory.
4. Street name. It must be present even if the street has no formal name; use whatever appears on the address certificate.
5. Country code. Usually set automatically, but verify it if you configured the entity manually.

Then move to the additional number to complete your data, not because it caused the warning. The difference between this order and a random one is measured in hours of work.

Verify your address data before your first invoice

Two steps, a few minutes, and they save you a full cycle of trial and error.

Step one: match against the official address certificate. Open the National Address certificate PDF, open your entity settings alongside it, and compare the six fields character by character. Small mismatches are the ones that slip through: a trailing space in the street name, or “Al Yasmin District” against “Al Yasmin.”

Step two: issue a test invoice. Use a testing environment before going live, issue a nominal-value invoice to a test customer, and watch the response. A standard tax invoice should be cleared, and a simplified one reported. Any address warning gets resolved here, before it reaches a real customer.

Do this once at setup and your data stays stable for every invoice after it.

Common mistakes when filling in the additional number

• Swapping the building number and the additional number. Both are 4 digits, so it is easy to put one in the other’s box. Copy them in the order shown on the address certificate.
• Entering fewer than 4 digits. If your number is 742, write it as 0742 with all four digits.
• Using an old address after relocating. An entity that moved but never updated its National Address issues invoices whose data no longer matches its records.
• Using Arabic-Indic digits. Use Latin digits (0 through 9) only.
• Using head-office address data on a branch invoice. Each branch has its own National Address.
• Relying on Google Maps. Maps do not show the official additional number.

Individuals and business owners

The structure is identical. The context differs.

For individuals, the additional number is needed to receive shipments, open a bank account, register a vehicle, and update Absher records. Carriers rely on it for the last-mile step, and without it a shipment may return to the warehouse.

For business owners, the additional number forms part of the National Address data required for:

• Issuing or renewing a commercial registration.
• Registering for value added tax with the authority.
• Registering on the Balady platform for a municipal licence.
• Opening a commercial bank account.
• Registering with the General Organization for Social Insurance (GOSI).

If your business operates from leased premises, use the leased address rather than your home address. If you work from home as a sole establishment, use your home address and mark the premises as home-based during registration.

Impact on shipping and logistics

Outside invoicing, the additional number is the precision element carriers depend on to fix a delivery point. A complete National Address translates into coordinates a delivery system reads directly, instead of the manual description that prevailed before the addressing system existed.

For online stores the operational effect is direct: an incomplete address means a failed delivery attempt, then a call to the customer, then a second attempt that may carry a fee. That is why most store platforms ask for postal code, building number, and additional number on the shipping page rather than settling for a district name. If you are weighing the operational cost of getting this wrong against system costs, our e-invoice pricing comparison puts the numbers side by side.

The additional number and tax audits

During a tax audit, the auditor compares the address registered in your VAT file against the address shown on invoices issued in the period under review. Matching here is a matter of data discipline, and any discrepancy calls for an explanation.

Keep the National Address certificate stored electronically with your entity records, and review it whenever your premises change. Full details of the wider system sit on our e-invoicing page, and the regulatory staging is covered under ZATCA Phase Two integration.

How Qoyod helps you keep National Address data clean

Qoyod is compliant with Phase 2 of e-invoicing, and its role here is operational:

• Configure entity data once. Enter your National Address components in entity settings, and they are used automatically in every subsequent invoice file instead of being re-entered.
• Customer address completeness checks. In the June 2026 update, the customer create and edit form was improved to ensure address data is complete against the authority’s requirements, reducing warnings and rejections caused by missing address data.
• 10 smart compliance alerts that review an invoice before it goes to the Fatoora platform, including prompts for missing address data. The alerts are non-blocking, meaning they warn you without stopping the operation, so they reduce the risk of rejection rather than guaranteeing acceptance.
• A simulation environment for testing your setup and invoices before going live, so missing address data surfaces before your first real invoice.
• Multi-branch management, where each branch keeps its own data so every branch invoice carries the correct address.
• Authority integration for exchanging invoices: immediate clearance for standard tax invoices, and reporting within 24 hours for simplified ones.

The effect is that address data stops being a field you re-check on every invoice and becomes a setting you configure once, with the system passing it through and flagging gaps. For the underlying terminology, see ZATCA e-invoicing and e-invoicing (Fatoora).

Frequently asked questions

What is the additional number in the Saudi National Address?

A 4-digit number issued by Saudi Post for each building, representing the building’s precise location coordinates. Its formal name in National Address documentation is the “secondary number,” while “additional number” is the common name for the same figure.

Is the additional number mandatory on an e-invoice?

The published validation rules check the seller address for six elements: street name, building number, district, city, postal code, and country code. The additional number is not among the checked elements, but filling it in is still advised because it is part of your registered National Address and because validation rules can be updated.

What is the difference between the additional number and the unit number?

The additional number locates the building on the map, while the unit number identifies the apartment or office inside the building. The common description of the additional number as identifying a unit within a building is inaccurate.

Is the additional number free?

Yes. Issuing a National Address and its additional number is free through the Saudi Post platform or the National Address app, and there is no fee to update it when your premises change.

Does the additional number stay the same or change?

It stays the same for a given building. It changes in limited cases such as demolition and rebuilding, or land re-subdivision under an urban development project.

How do I find my additional number?

Sign in to the National Address platform through the National Single Sign-On and pin your building on the map. The system derives the additional number from the location coordinates and issues an address certificate as a PDF.

Can several businesses share the same additional number?

Yes, if they genuinely operate from the same building. Each entity still holds its own commercial registration and tax number. This is common in offices that manage several entities from one location.

Do I need the buyer’s additional number on a simplified invoice?

No. The buyer-address rule does not apply to simplified tax invoices and their notes. Even on a standard tax invoice issued to a business, the buyer-address requirement in the validation rules is limited to street, city, and country code.

Conclusion

The additional number is four digits that fix your building’s location precisely, and its formal name is the secondary number. Fill it into your entity data and your customer records, and keep your National Address certificate current. But know its limits: if an invoice is rejected for an address reason, start with the district, postal code, and building number, because those are the fields validation genuinely checks. Diagnosing the right field saves far more time than editing a healthy one.