Tax law for SAP: the rules that change your system
Nine areas, 290 entries and the official text of each rule: consumption tax reform, electronic tax documents, SPED, ICMS, ISS, PIS and Cofins, IRPJ and CSLL, foreign trade, and the SAP and NTT DATA maintenance cycle. Each entry says what the rule covers, whether it is in force and what it asks of the system.
From the IBS taxable event to the invoice layout, from the EFD file to the end of ECC maintenance: what changes, when it changes and where the valid text is.
Find the law by your role
Five entry points, one per role, to reach the right part of the library fast.
01Tax management and controllership
The dates ahead, the calendar of the nearest changes and the area that answers each close question.
Go to section02SAP IT
Technical notes, layouts and versions that change the system, and the path from a rule to the configuration.
Go to section03Accounting and bookkeeping
EFD, ECD, ECF, DCTFWeb and fines: the SPED area and what each file requires from the company.
Go to section04Legal and compliance
The hierarchy of rules, who publishes each one and the official source you cite in an opinion or an audit.
Go to section05Management and project leadership
The reform timeline from 2023 to 2033 and the SAP maintenance dates that go into the plan.
Go to sectionDirect links
Nine areas, one entry per rule and the official source next to it
The legislation behind SAP tax is split into nine areas, and each rule has an entry with what it covers, its status and the point to watch for whoever runs the system.
What it covers
The subject of the rule in plain words, with the article or item that matters to the system.
Status
In force, with the effective date, repealed or changed by another rule, always naming the rule that changed it.
Watch point for SAP users
The part of the system the rule touches: master data, calculation, document, bookkeeping or file.
Official text
The link to the body that published it: Planalto, Confaz, CGIBS, Receita Federal, the NF-e and SPED portals, SAP or NTT DATA.
The entries are short on purpose. Whoever needs the full text follows the official link; whoever needs to decide what to do in SAP continues to tax setup or to the SAP Tax Diagnostic.
Choose the area and open the entries
Each card shows how many entries the area has today and what it covers. There are nine areas, from reform and documents to taxes, foreign trade and SAP.
Consumption tax reform
The amendment, complementary laws, CBS and IBS regulations, joint acts and the 2026 to 2033 transition.
Open the area 35entries in 5 groupsElectronic tax documents
SINIEF adjustments and technical notes for documents such as the NF-e, NFC-e, CT-e, MDF-e and NFS-e.
Open the area 24rules in 9 groupsSPED and ancillary obligations
EFD, ECD, ECF, DCTFWeb, eSocial and the fines for late and wrong filing.
Open the area 31rules in 5 groupsICMS, agreements and benefits
Credit and CIAP, benefits by agreement and by state, DIFAL, tax substitution and the transition.
Open the area 22rules in 6 groupsISS and NFS-e
The municipal service tax, the national-standard service invoice and the move to IBS.
Open the area 32rules in 7 groupsPIS and Cofins
Cumulative and non-cumulative regimes, credits, withholdings, EFD-Contribuições and the replacement by CBS.
Open the area 37rules in 9 groupsIRPJ and CSLL
Actual, presumed or arbitrated profit, interest on equity, loss offsetting and subsidies.
Open the area 39rules in 8 groupsForeign trade and customs
Import and export: Customs Regulation, Duimp, DU-E, drawback and regimes that suspend tax.
Open the area 34entries in 6 groupsSAP, NTT DATA and income tax
ECC and S/4HANA maintenance, NTT DATA statements about GUEPARDO Tax, and income tax.
Open the areaTo take the rule to the system, each new tax has its own project page.
- ISS and NFS-e: see ISS calculation and the national-standard NFS-e.
- PIS and Cofins: EFD-Contribuições in SAP.
- IRPJ and CSLL: IRPJ and CSLL calculation.
- Foreign trade: import and Duimp in SAP.
Which rules cover which topics
A tax topic rarely fits in one area. The grid shows, across the nine areas, where the central rule is and where the supporting ones are.
| Topic | Reform | Documents | SPED | ICMS | ISS | PIS and Cofins | IRPJ and CSLL | Foreign trade | SAP and NTT |
|---|---|---|---|---|---|---|---|---|---|
| CBS, IBS and Selective Tax | Main | Support | Not covered | Support | Support | Support | Support | Support | Support |
| Invoice and document layout | Support | Main | Support | Not covered | Support | Not covered | Not covered | Not covered | Support |
| Split payment | Main | Support | Not covered | Not covered | Not covered | Not covered | Not covered | Not covered | Not covered |
| Bookkeeping and digital files | Support | Not covered | Main | Support | Support | Support | Support | Not covered | Support |
| ICMS credit and calculation | Not covered | Not covered | Support | Main | Not covered | Not covered | Not covered | Support | Not covered |
| Tax benefits and incentives | Support | Not covered | Not covered | Main | Not covered | Support | Support | Support | Support |
| Tax substitution (ST) and DIFAL | Not covered | Not covered | Not covered | Main | Not covered | Not covered | Not covered | Not covered | Not covered |
| ISS and NFS-e | Support | Support | Not covered | Not covered | Main | Not covered | Not covered | Not covered | Not covered |
| PIS, Cofins and credits | Support | Not covered | Support | Not covered | Not covered | Main | Not covered | Support | Not covered |
| Profit, interest on equity and offsetting | Support | Not covered | Not covered | Not covered | Not covered | Not covered | Main | Not covered | Not covered |
| Import, export and customs regimes | Not covered | Not covered | Not covered | Support | Not covered | Support | Not covered | Main | Not covered |
| SAP maintenance and versions | Not covered | Not covered | Not covered | Not covered | Not covered | Not covered | Not covered | Not covered | Main |
| Income tax: subsidies and transfer pricing | Support | Not covered | Not covered | Not covered | Not covered | Not covered | Main | Not covered | Main |
Main means the area holds the central rules of the topic. Support means there is an entry that touches the topic, but the central rule is in another area. One topic usually crosses two or three areas: split payment, for example, starts in the reform law and reaches SAP through the invoice layout.
The consumption reform, from 2023 to 2033
Ten milestones, each with the rule that sets it.
- 2023
EC 132, of 20/12/2023
Creates IBS, CBS and the Selective Tax and sets in the ADCT the transition that runs from 2026 to 2033.
- 2025
LC 214, of 16/01/2025
Creates the IBS Steering Committee and establishes the three new taxes: IBS, CBS and Selective Tax. It has 544 articles, with staggered effective dates.
- 2026
Rate test and regulations
Test year: CBS at 0.9% and IBS at 0.1%, offset against PIS and Cofins (ADCT, art. 125). LC 227, Decree 12.955 (CBS) and CGIBS Resolution 6 (IBS) are issued.
- 2027
CBS and the end of PIS and Cofins
CBS and the Selective Tax start to be charged, PIS and Cofins are extinguished and IPI drops to zero, except for the Manaus Free Trade Zone (ADCT, art. 126).
- 2028
IBS at 0.05% plus 0.05%
In both years, IBS has 0.05% for the state and 0.05% for the city, while CBS loses 0.1 percentage point (ADCT, art. 127).
- 2029
ICMS and ISS at 9/10
The replacement begins: ICMS and ISS are worth 9/10 of their rates, and benefits fall in the same proportion (ADCT, art. 128).
- 2030
ICMS and ISS at 8/10
Second stage: ICMS and ISS are worth 8/10 of their rates (ADCT, art. 128). The Senate sets the reference rates by resolution (art. 130).
- 2031
ICMS and ISS at 7/10
Third stage: ICMS and ISS are worth 7/10 of their rates, and benefits follow the same proportion (ADCT, art. 128).
- 2032
ICMS and ISS at 6/10
Last stage before extinction: 6/10 of the rates (ADCT, art. 128). Any ICMS credit balance left in 2032 has its own treatment (ADCT, art. 134).
- 2033
End of ICMS and ISS
ICMS and ISS are extinguished in 2033, under the ADCT, art. 129. IBS remains in their place, next to CBS.
The reform has a reading order: the amendment says what changes, the complementary law says how, the regulations give the procedure and the joint acts give the date of each obligation. The year-by-year detail, with the calendar of documents, is on the page tax reform: CBS and IBS, and the entries for the rules are in the area Consumption tax reform.
The nearest changes, with the rule behind each date
Eleven dates from today, in order, each with the act or notice that sets it. For the deadline of each obligation, with the rule and the source, open the tax calendar.
| Date | What happens | Rule or notice | Area |
|---|---|---|---|
| 15/10/2026 | Integration tests begin between payment service providers (PSPs) and the Public Split Payment Platform, in a controlled environment and with no effect on real operations. | Receita Federal, notice on the start of split payment tests | Reform |
| 26/10/2026 | NF-e technical notes 2025.002 v1.52, 2026.007 v1.10 and 2026.008 v1.00 enter the test environment, after the date of 05/10 was postponed. | Notice of 05/10/2026 on the NF-e portal | Documents |
| 01/11/2026 | ICMS Agreement 107/26 takes effect: it splits NCM 8516.60.00 in Annex XX of ICMS Agreement 142/18, with its own CEST for stoves and parts. It does not apply to São Paulo. | ICMS Agreement 107/26, published in the Federal Official Gazette (DOU) of 09/09/2026 | ICMS |
| 13/11/2026 | The PSP registration forms for the split payment tests close. Registrations for the other PSPs open on 16/11/2026. | Receita Federal, notice on the start of split payment tests | Reform |
| 15/11/2026 | First delivery of the monthly periodic events of the DeRE (Declaration of Specific Regimes), for the assessment period of October 2026. | Joint Act RFB/CGIBS 4/2026, art. 1, XVII and § 5 | Documents |
| 16/11/2026 | NF-e technical notes 2025.002 v1.52, 2026.007 v1.10 and 2026.008 v1.00 take effect in production. | Notice of 05/10/2026 on the NF-e portal | Documents |
| 01/12/2026 | NFS-e becomes mandatory for digital platforms, leases, intangible goods, condominiums and other services, together with the gas, water and real estate sale invoices. | Joint Act RFB/CGIBS 4/2026, art. 1 | Documents |
| 01/01/2027 | CBS and the Selective Tax start to be charged and PIS and Cofins are extinguished. | EC 132/2023, ADCT, art. 126 | Reform |
| 01/01/2027 | Electronic tax documents become mandatory for Simples Nacional taxpayers, for the NF-e of single-phase operations and for the Duimp. | Joint Act RFB/CGIBS 4/2026, art. 1 | Documents |
| 01/01/2027 | The layout of Technical Note 2026.001 of the EFD ICMS/IPI takes effect. | COTEPE/ICMS Act 69/26 | SPED |
| 31/12/2027 | Mainstream maintenance of SAP Business Suite 7, where ECC sits, ends. Optional extended maintenance runs to 31/12/2030. | SAP News, announcements of 04/02/2020 and 07/10/2026 | SAP and NTT |
Dates for documents and technical notes change by notice, like the one on 05/10/2026 that postponed three NF-e technical notes. The valid date is the one in the latest act or notice on the body's portal.
How rules are ordered, from the amendment to the technical note
Six levels. Knowing which level a rule sits on tells you how much it can change and who publishes it.
1. Constitution and amendments
They define the taxes and the transition. EC 132/2023 is the parent rule of the consumption reform.
2. Complementary laws
They bring the general rules: LC 214, 227 and 235 for IBS and CBS; LC 87, 24, 160 and 190 for ICMS.
3. Decrees and regulations
They detail the procedure. Decree 12.955/2026 is the CBS regulation and CGIBS Resolution 6/2026 is the IBS one.
4. Joint acts and ordinances
They set dates, ancillary obligations and technical documentation. They come from the Receita and the CGIBS, together or separately.
5. Confaz agreements and adjustments
For ICMS: agreement for benefits and tax substitution, SINIEF Adjustment for documents and EFD, COTEPE Act for the layout.
6. Technical notes and guides
They say how the document or file is built: fields, validation rules and versions. They change more often.
The higher rule prevails over the lower one, and the lower one tends to change more. So a project follows technical notes every month and regulations with each new act.
When each document starts to carry IBS and CBS
Joint Act RFB/CGIBS 4/2026, of 30/07/2026, sets the start dates for mandatory issuance.
| Start of obligation | Documents | Note |
|---|---|---|
| 03/08/2026 (already started) | Non-urban transport BP-e, NFS-e Via, DC-e (99), NF3e (66), GTV-e (64), MDF-e (58), CT-e OS (67), CT-e (57), NFC-e (65) and NF-e (model 55) | Counts the taxable event that occurs on or after the date. |
| 01/10/2026 (already started) | NFCom (62), DIR, DeRE Taxpayer Table and NFS-e for the LC 116 list services not covered by the other items | The NFS-e for the LC 116 list services follows the same date. |
| 15/11/2026 | Monthly periodic events of the DeRE | The first period delivered is October 2026, due on the 15th of the following month. |
| 01/12/2026 | NFS-e for digital platforms, leases, intangible goods, condominiums and other services; NFGas (76), NFAg (75), NF-e ABI (77); semi-urban and air BP-e; NF-e of non-ICMS taxpayers | More than one document changes on the same date. |
| 01/01/2027 | Simples Nacional taxpayers, NF-e of single-phase operations, Duimp and other DeRE events | Whoever imports a physical good follows the Duimp date, not the NF-e date. |
The table summarizes Joint Act RFB/CGIBS 4/2026. The documents, layouts and technical notes of each one are in the area Electronic tax documents, and the filling of CST and cClassTrib can be checked in the tool CST and cClassTrib table.
Six steps between the published rule and the SAP proven
The path is the same for any area: what changes is the rule and the part of the system it touches.
- 01
Identify the rule and its effective date
Which rule, which article and from when it applies, according to the official act.
- 02
The client decides the position
The company, with its tax team and advisers, decides how the rule applies to each operation.
- 03
Design the behavior
Turn the decision into a system rule: master data, tax determination, document and bookkeeping.
- 04
Configure SAP
Set up and, when needed, adjust the tax ABAP code, with the right effective date.
- 05
Prove with test cases
Compare each result with the expected value written by the tax team and keep the evidence.
- 06
Follow the next change
Technical notes, notices and new acts go into a calendar, and each one triggers an impact assessment.
Steps 3 to 5 are the setup and test work described in tax setup in SAP and in tax testing in SAP. Step 6 is what AMS Fiscal maintains after go-live.
Your project question and the area that answers it
Nineteen questions that come up in SAP tax projects and where the rule is.
| Project question | Area | Rules that usually answer |
|---|---|---|
| Which rule created CBS and IBS and what are the dates? | Consumption reform | LC 214/2025, LC 227/2026 and EC 132/2023 |
| Who is the taxpayer, what is the taxable event, the base and the credit? | Consumption reform | LC 214/2025, arts. 3 to 57 |
| How does split payment work? | Consumption reform | LC 214/2025, arts. 27 to 37; Joint Act RFB/CGIBS 2/2026 |
| Which technical note changes the NF-e and NFC-e fields? | Electronic documents | NT 2025.002, NT 2026.007, NT 2026.008 |
| When do CT-e, MDF-e and NFS-e carry IBS and CBS? | Electronic documents | Joint Act RFB/CGIBS 4/2026; CT-e and NFS-e technical notes |
| Which version of the EFD guide is in force? | SPED and obligations | COTEPE/ICMS Act 44/18, amended by 86/26 |
| What is the deadline for ECD, ECF, EFD-Contribuições and EFD-Reinf? | SPED and obligations | IN RFB 2.003/21, 2.004/21, 1.252/12 and 2.043/21 |
| What is the fine for late or wrong ancillary obligations? | SPED and obligations | MP 2.158-35/2001, Law 10.426/2002, Law 8.212/1991 |
| How do the ICMS credit and its reversal work? | ICMS and benefits | LC 87/1996, arts. 19 to 21 and art. 20, § 5 |
| Is a state benefit still valid, and until when? | ICMS and benefits | LC 24/1975, LC 160/2017, ICMS Agreement 190/17 |
| How is DIFAL calculated on a sale to a final consumer? | ICMS and benefits | LC 190/2022, ICMS Agreement 236/21 |
| How does tax substitution work between states? | ICMS and benefits | ICMS Agreement 142/18 |
| Where is ISS due and how does the national-standard NFS-e work? | ISS and NFS-e | LC 116/2003, LC 175/2020, CGNFS-e resolutions |
| Which revenues generate PIS and Cofins credit and how does EFD-Contribuições record them? | PIS and Cofins | Laws 10.637/2002 and 10.833/2003, IN RFB 1.252/2012 |
| What does the law say about interest on equity, presumed profit and subsidies? | IRPJ and CSLL | Law 9.249/1995, Law 9.430/1996, Law 14.789/2023 |
| When does the Duimp replace the DI and how does drawback suspend the tax? | Foreign trade | Coana Ordinance 165/2024, Law 11.945/2009, Customs Regulation |
| For how long does SAP maintain ECC and S/4HANA? | SAP and NTT | SAP announcements of 04/02/2020 and 07/10/2026 |
| How to read the NTT DATA statements about GUEPARDO Tax? | SAP and NTT | NTT DATA pages and posts, product statements |
| How does the investment subsidy credit work? | SAP and NTT | LC 214/2025, art. 534, and Law 14.789/2023 |
The body publishes the rule, the client decides the position and the system is the proof
What DFSpro does
- Shows the rule, the status and the official source of each point that touches SAP.
- Designs and configures in SAP the behavior the company decided on.
- Proves, with documents and test cases, what the system calculates, issues and records.
- Follows changes in technical notes and acts after go-live.
What stays with the client
- Reading the rule and defining the tax position for each operation.
- The decision to apply or not a benefit, a regime or a deadline.
- The legal opinion, when the rule leaves doubt.
- Approving the result and answering to the tax authority.
DFSpro designs and configures the behavior of the system and proves it in testing. The tax decision always belongs to the client. The entries describe what the rule says and where it is; they do not indicate the position the company should adopt.
Where each rule comes from and where to look
The same subject can have rules from more than one body, and the effective date is usually in the act, not in the news.
| Body or source | What it publishes | Where to look |
|---|---|---|
| Planalto | Constitution, amendments, laws, complementary laws and decrees | Federal legislation, consolidated text |
| Confaz | ICMS Agreements, SINIEF Adjustments and COTEPE/ICMS Acts | Confaz legislation, by type and by year |
| CGIBS (IBS Steering Committee) | Resolutions, regulations, ordinances and joint acts with the Receita | Legislation on the CGIBS portal |
| Receita Federal | Normative instructions, notices, reform manuals and joint acts | Receita rules and news |
| National NF-e Portal | Technical notes, technical bulletins, notices and tables such as the CST and cClassTrib one | Portal legislation and documents |
| SPED Portal | Practical guides, layouts, validators, notices and technical notes for EFD, ECD, ECF and EFD-Reinf | Portal modules |
| NFS-e Portal | NFS-e technical documentation and CGNFS-e resolutions | Portal library |
| SAP | Maintenance announcements and correction notes | SAP News and support portal |
| NTT DATA | Statements about GUEPARDO Tax, a product of NTT DATA | Product page and blog |
| Federal Official Gazette (DOU) | Publication of acts that only take effect once published | National Press (Imprensa Nacional) |
Rules and notices behind the dates
Each date and each article cited has its official text below.
Planalto
CGIBS and Receita Federal
Portals and Confaz
Frequently asked questions about tax law in SAP
Choose the area5 questions, 01 to 05
01Where to start if the company has never organized its SAP tax legislation?+
With the question that hurts at close. If it is a rejected invoice, the electronic documents area. If it is a refused EFD file, the SPED one. If it is a benefit or DIFAL, the ICMS one. If it is ISS, PIS and Cofins, IRPJ and CSLL or import and export, the area of that tax. If it is the 2026 and 2027 change, the consumption reform one. The topic grid shows where each subject has its central rule.
02Does the library replace consulting the Official Gazette or legal advisers?+
No. The entry summarizes what the rule covers and points to the official text, which is the one that counts. Interpreting the rule and deciding the position are the responsibility of the company and its advisers. The library shortens the path between the subject and the text, and shows the point SAP needs to reflect.
03What is the difference between a law, a joint act and a technical note?+
The law defines the tax and the general rules. The joint act, signed by the Receita and the CGIBS, sets dates and obligations. The technical note says how to build the document or file, with fields and validations. The law changes little; the technical note changes often, so it needs continuous follow-up in SAP.
04How many entries are there and how are they organized?+
There are 290 entries in nine areas. Each area splits its entries by group, such as laws and regulations in the reform, NF-e, NFC-e and CT-e in documents, or regimes and clearance in foreign trade. Each entry gives what the rule covers, its status, the watch point for whoever runs SAP and the link to the official text.
05Who in the company should read each area?+
Tax management reads the reform, ICMS, ISS and PIS and Cofins, accounting reads SPED and IRPJ and CSLL, SAP IT reads electronic documents and technical notes, and the foreign trade team reads the customs area. Legal checks the hierarchy and the official source, and management follows the timeline. The index by role, at the top of the page, points each person the way.
Reform and deadlines5 questions, 06 to 10
06When do CBS and IBS really start to apply?+
In 2026 there is a test phase: CBS is at 0.9% and IBS at 0.1%, and what is paid is offset against the PIS and Cofins due. CBS starts to be charged in 2027, with a 0.1 percentage point reduction in 2027 and 2028, when PIS and Cofins are extinguished. IBS comes in gradually: 0.05% state and 0.05% city in 2027 and 2028, and then it replaces ICMS and ISS from 2029 to 2033, under arts. 125 to 129 of the ADCT.
07What changes in 2026 for whoever issues invoices?+
Joint Act RFB/CGIBS 4/2026 set the start of mandatory documents with IBS and CBS: 03/08/2026 for NF-e, NFC-e, CT-e and MDF-e, among others, 01/10/2026 and 01/12/2026 for the other invoices, and 01/01/2027 for Simples Nacional. The technical notes and the CST and cClassTrib of each item need to be in the system.
08When do ICMS and ISS end?+
The amendment cuts the ICMS and ISS rates to 9/10 in 2029, 8/10 in 2030, 7/10 in 2031 and 6/10 in 2032, and extinguishes them from 2033 (ADCT, arts. 128 and 129). Tax benefits fall in the same proportion. Until then, the two taxes coexist with CBS and IBS, and SAP needs to handle both worlds.
09What is split payment and when do the tests start?+
It is the division of payment in which the tax is separated at settlement, regulated in arts. 27 to 37 of LC 214/2025. On 30/09/2026, the Receita Federal announced that integration tests between the PSPs and the Public Platform start on 15/10/2026, in a controlled environment and with no effect on real operations.
10Can the dates change? How to follow them?+
They can, and they already have. On 05/10/2026 the NF-e portal postponed three technical notes, which enter the test environment on 26/10/2026 and production on 16/11/2026. The safe way is to follow each body's portal on a set schedule and record an impact assessment for each change.
SAP, files and versions4 questions, 11 to 14
11Does the SAP update solve a rule change on its own?+
Usually not. The update delivers calculation rules and layouts, but the company still decides the tax treatment of each operation, maintains the master data and the validity of the rules, and checks the result. So each change needs verified setup and a test in the company's own environment.
12Which version of the EFD ICMS/IPI Practical Guide is in force?+
Version 3.2.4, under COTEPE/ICMS Act 86/26, published on 10/09/2026 and in force on publication. The layout of Technical Note 2026.001 takes effect from 01/01/2027, under COTEPE/ICMS Act 69/26. For each period, keep the guide version used to generate the file.
13For how long does SAP maintain ECC and S/4HANA?+
SAP states that mainstream maintenance of Business Suite 7, which includes ECC, runs to 31/12/2027, with optional extended maintenance to 31/12/2030, and that the dates did not change on 07/10/2026. For S/4HANA, the maintenance commitment announced on 04/02/2020 runs to the end of 2040.
14How to read the NTT DATA statements about GUEPARDO Tax?+
NTT DATA, the owner of the product, describes the scope, seals and achievements of GUEPARDO Tax on its own pages and posts. These are statements by the product owner, not technical proof of behavior in the company's SAP. Proof comes from testing in the client's environment.
Contracting and limits4 questions, 15 to 18
15Does DFSpro say which rule or which position I should follow?+
No. The tax decision belongs to the client. DFSpro shows the rule and the source, designs and configures the SAP behavior the company decided on and proves, with test cases, what the system calculates, issues and records.
16How does DFSpro use the legislation in the project?+
The rule is the reference for each configured rule. In the diagnostic, it shows where the system differs from the current rule; in setup, it defines the validity of each table; in testing, it supports the expected value; after go-live, it guides the follow-up of changes.
17Do the entries serve as audit evidence?+
They serve as a starting point: each entry cites the rule and the official text. Audit evidence is the link between the rule, the expected value, the test case and the system result, with an owner and a date. That record is made in the project, from the entry.
18How to ask for help with a specific rule?+
Through the contact page, giving the rule and the SAP point it touches, such as master data, calculation, document or file. The conversation sets whether the path is diagnostic, setup, testing or follow-up.
Bring to the project the rule your SAP still does not prove
Choose the rule that weighs most on your close and bring the case. The conversation covers the part of the system it touches and the path to configure and prove it.
For more depth: CST and cClassTrib table and Tax readiness checklist.