Key takeaways
- Multi-state sales tax is a six-step cycle per state: monitor nexus, register, calculate, file, remit and keep records.
- Software can automate most data work, but registration decisions, product taxability and notices still need people.
- In the 24 Streamlined Sales Tax states, qualifying remote sellers can get calculation, filing and remittance from a Certified Service Provider at no charge.
In short: To automate US sales tax filing in every state, connect your sales data to software that monitors economic nexus thresholds, calculates tax by address, prepares and files returns in each state, remits payment and archives the records. Software can handle most of the repetitive work. You still decide when to register, how products are taxed and how to answer notices. In the 24 Streamlined Sales Tax states, a Certified Service Provider may do calculation, filing and remittance at no cost for qualifying remote sellers.
Updated October 2026: This guide reflects Kentucky dropping its 200-transaction test on August 1, 2026, Illinois dropping its test on January 1, 2026, and the current 2025–2026 Streamlined Sales Tax CSP contract.
What does multi-state sales tax compliance involve?
Multi-state sales tax compliance is a repeating cycle of six steps, and each step happens separately in every state where you have nexus. Since the Supreme Court's South Dakota v. Wayfair ruling on June 21, 2018, a seller can owe tax in a state through sales alone, without any office or stock there. Today all 45 states with a statewide sales tax have economic nexus rules.
- Monitor nexus. Track sales into each state against its economic nexus threshold, and track physical presence such as staff or inventory.
- Register. Get a sales tax permit before you start collecting in a state.
- Calculate and collect. Charge the right state and local rate on each taxable sale, based on the delivery address and the product.
- File. Submit a return to each state on the schedule it assigns you.
- Remit. Pay the tax collected by each state's deadline.
- Keep records. Store transactions, exemption certificates, returns and payment proofs for audits.
For background on the rules themselves, see our VAT and US sales tax compliance guide.
Which sales tax steps can software automate?
Software can automate most of the data work in every step, but some decisions stay with you or your adviser. The table shows the typical split.
| Step | What software does | What stays manual |
|---|---|---|
| Nexus monitoring | Totals sales per state over each state's measurement period and alerts you as you approach or pass a threshold | Telling the tool about physical presence (staff, inventory, events) and deciding the registration date |
| Registration | Pre-fills applications, tracks permit numbers and filing frequencies | Signing applications, supplying officer details and handling state questions |
| Calculation | Validates the address, assigns the tax jurisdictions and applies the current combined rate | Mapping products to taxability categories and collecting exemption or resale certificates |
| Filing | Turns transactions into return data for each state and files electronically | Reviewing returns, approving filings and correcting source data errors |
| Remittance | Pays each state by its deadline, often by debit from a funded account | Keeping enough funds available and authorising payments |
| Records and notices | Archives returns, payment confirmations and transaction data | Answering notices and audits, often with an adviser |
How does automated nexus and threshold monitoring work?
Automated nexus monitoring compares your running sales totals in each state with that state's threshold and measurement period. The rules are not uniform, which is why spreadsheets break down at scale.
- Different amounts. Many states use $100,000 in sales. Texas uses $500,000 in total Texas revenue over the preceding 12 months, and California uses $500,000.
- Different tests. Some states still add a transaction count, but the trend is to drop it. Alaska's remote seller commission removed its 200-transaction test on January 1, 2025, Utah on July 1, 2025, Illinois on January 1, 2026 and Kentucky on August 1, 2026.
- Different periods. States measure over the previous or current calendar year, or a rolling 12 months. From 2026, Illinois asks retailers to check the $100,000 test on a rolling quarterly basis.
- Different deadlines. Texas expects you to hold a permit and collect tax no later than the first day of the fourth month after you pass its threshold.
A good monitoring tool stores these rules per state, updates them when laws change and shows the date you crossed each threshold. Check the current figures in our economic nexus by state guide. If you sell from outside the US, our guide to US sales tax for foreign sellers covers the extra steps.
Can you register for sales tax in many states at once?
You can register in up to 24 states at once through the Streamlined Sales Tax Registration System (SSTRS); every other state needs its own application. Streamlined Sales Tax (SST) has 23 full member states and one associate member, Tennessee.
Outside the SST states, registration is state by state. Software and service providers can prepare the forms and track deadlines, but each state reviews and approves its own permit.
How does software calculate the right sales tax rate?
Software calculates the rate by validating the delivery address, assigning it to every taxing jurisdiction that applies, and adding up the state and local rates for that product. This matters because local rates change often and can follow district lines rather than ZIP codes. Address-level ("rooftop") assignment is more accurate than a ZIP-code lookup.
Rates vary widely. As of July 1, 2026, Louisiana had the highest average combined rate at 10.13%, according to the Tax Foundation. Five states have no statewide sales tax, although Alaska allows local taxes. See our guides to the highest and lowest sales tax rates and the states with no sales tax.
Some states offer shortcuts for remote sellers. Texas lets remote sellers elect a single local use tax rate of 1.75% instead of tracking each local rate. Exempt sales also need proof: if a buyer gives you a resale certificate, your system should store it and link it to the buyer.
How often do you have to file sales tax returns?
Each state assigns your filing frequency, usually monthly, quarterly or annually, based on how much tax you collect there. You do not choose it. A seller in 20 states can have 20 different calendars, which is the main reason filing is worth automating.
Texas is a typical example. It tells you your frequency by letter after it approves your permit.
| Texas filing frequency | Period | Due date |
|---|---|---|
| Monthly | Each calendar month | 20th of the following month |
| Quarterly | January–March, April–June, July–September, October–December | April 20, July 20, October 20, January 20 |
| Yearly | Previous calendar year | January 20 |
Missed dates cost money. Texas charges $50 for each report filed late, plus 5% of the tax if you pay 1 to 30 days late and 10% if you pay more than 30 days late. If a due date falls on a weekend or holiday, Texas moves it to the next working day. Other states use different rules, so your tool should hold each state's calendar.
What is Streamlined Sales Tax, and can a CSP file for you?
Streamlined Sales Tax is an agreement among states to simplify sales tax, and its Certified Service Providers (CSPs) can calculate, file and remit tax for you in member states. The SST Governing Board currently lists six certified providers: AccurateTax, Avalara, Avior, Exactor, Sovos and TaxCloud. SST notes that Exactor is not currently offering free services under the CSP program.
If you qualify as a "CSP-compensated seller" in a member state, the state pays the CSP, and the CSP may not charge you for these services in that state:
- setting up and integrating the certified system with yours
- calculating tax at the time of sale
- preparing and filing returns
- making remittances
- responding to sales and use tax notices and audits
To qualify, you register through the SSTRS, contract with a CSP and meet criteria about having little or no property, payroll or fixed place of business in that state. A remote seller that must collect only because it meets a state's economic nexus threshold also qualifies. The CSP can still charge for non-member states and for services outside the contract. The current contract covers 2025–2026, so ask any CSP what it offers now.
How do marketplace facilitator laws change what you file?
Marketplace facilitator laws make platforms such as Amazon collect and remit tax on the sales they facilitate, so you file mainly for your direct sales. Missouri's law took effect on January 1, 2023, the last of the 45 sales tax states to adopt economic nexus rules.
The details still vary by state:
- In Texas, a remote seller that sells only through marketplace providers that collect the tax does not need a permit. It must still keep records of those sales for at least four years.
- Some states count marketplace sales toward your own threshold. Others do not.
- If you also sell on your own website, you must collect and file for those sales yourself.
Your software should tag each sale by channel. That way it can exclude marketplace-collected sales from your returns while still counting them for nexus where a state requires it.
What types of sales tax automation tools are there?
Sales tax tools fall into three broad groups, and many businesses use more than one.
- Calculation engines, such as Avalara, Vertex and TaxJar, plug into checkouts, ERPs and billing systems to return a rate on each transaction. Many also offer filing.
- Filing and compliance services take your transaction data, prepare returns, file and pay. Some combine software with a managed service and registration help.
- Accounting firms and service providers handle registration, filing and notices for clients, often using one of the tools above.
The right mix depends on where your data lives, how many states you file in and how much you want to manage in-house.
How do you choose a tool to file sales tax in every state?
Choose a tool by checking whether it covers every step of the workflow for every state you sell into, using your real data sources. Use this checklist when comparing options.
| Capability | Why it matters | Question to ask |
|---|---|---|
| Data imports | Returns are only as good as the transaction data behind them | Can it import from our platforms (for example Shopify, Amazon, Stripe) and from spreadsheets? |
| Address validation and rooftop rates | ZIP-code lookups can assign the wrong local rate | Does it validate addresses and assign jurisdictions at address level? |
| Nexus monitoring | Thresholds and tests change, as Kentucky and Illinois showed in 2026 | Does it track physical and economic nexus per state and show the date we crossed each threshold? |
| Filing in all states | Gaps force you back to manual filing | Does it file in every state and locality where we are registered, including home-rule jurisdictions? |
| Remittance | Late payment carries penalties and interest | Does it pay each state by the deadline, and how is the payment funded? |
| Audit trail | States can audit several years back | Does it keep returns, payment proofs and transaction detail for each period? |
| Registration support | You must hold a permit before collecting | Does it help register in new states? |
| Canada GST/HST | Many US sellers also sell into Canada | Can it handle Canadian GST/HST in the same place? |
How does Taxually handle multi-state sales tax?
Taxually handles US and Canadian sales tax through LumaTax. LumaTax is currently available to enterprises and to accounting firms and other service providers. E-commerce sellers can join a waiting list. LumaTax covers:
- nexus analysis for physical and economic nexus
- help with state sales tax registration
- data imports from Excel, Stripe, Amazon and Shopify
- address validation and jurisdiction assignment
- return preparation, with return summaries
- automated filing with state authorities, and payment
- a document archive for returns and records
- Canadian GST/HST alongside US sales tax
Businesses that also sell into Europe can manage VAT through the same Taxually platform.
Sources
- Streamlined Sales Tax Governing Board: CSP free services and CSP-compensated sellers
- Streamlined Sales Tax: SSTRS registration FAQ
- Texas Comptroller: Remote sellers
- Texas Comptroller: Sales and use tax (due dates and penalties)
- Illinois Department of Revenue: Bulletin FY 2026-12
- PwC: Kentucky HB 757 removes the transaction threshold
- Utah Legislature: S.B. 47 (2025)
- Tax Foundation: State and local sales tax rates, midyear 2026
Frequently asked questions
How do you automate sales tax filing in every US state?
Connect your sales data to software that monitors economic nexus thresholds, calculates tax by address, prepares and files returns in each state, remits payment and archives the records. You still decide when to register, how products are taxed and how to answer notices.
Can sales tax software monitor economic nexus thresholds automatically?
Yes. Nexus monitoring tools total your sales per state over each state's measurement period and alert you as you approach or pass a threshold. You still need to tell the tool about physical presence such as staff or inventory.
How often do you file sales tax returns?
Each state assigns a monthly, quarterly or annual frequency, usually based on how much tax you collect there. In Texas, monthly returns are due on the 20th of the following month.
Do Certified Service Providers file sales tax for free?
In the 24 Streamlined Sales Tax states, a CSP-compensated seller can get calculation, filing, remittance and audit support at no charge, because the state pays the CSP. CSPs can charge for non-member states and for other services, and SST notes that Exactor is not currently offering free services.
Do I need to file sales tax if I only sell on Amazon?
Often not, because marketplace facilitator laws make the platform collect and remit the tax. In Texas, a remote seller selling only through collecting marketplaces does not need a permit but must keep records for at least four years. Rules vary by state, and direct sales are always your responsibility.
Does Taxually offer US sales tax filing?
Yes, through LumaTax, which covers nexus analysis, registration help, data imports, address validation, return preparation, filing, payment and a document archive for the US and Canada. LumaTax is currently available to enterprises and accounting/service providers, and e-commerce sellers can join a waiting list.
