On the heels of the tax reform bill passed in 2017, US taxation topped online staffing provider Upwork’s first-quarter list of the 20 fastest-growing skills. The first tax filing season affected by the new tax law also spurred demand for financial planning specialists and certified public accountants, which ranked No. 6 and No. 16 respectively.

The Upwork Skills Index calculates year-over-year growth rates based on freelancer billings through Upwork in the quarter versus the same quarter in the prior year.

Hadoop — an open source software used to store, process and analyze big data applications — was the second fastest-growing skill out of more than 5,000 skills freelancers provide on Upwork. And robotic process automation, in the third spot, earned a spot on the index for the first time.

Skills categories on the list in the first quarter all experienced more than 170% year-over-year growth; the top 10 grew more than 370%.

“Labor markets overall are tightening, and for many skills, employers are increasingly struggling to find available workers in their local areas,” said Upwork CEO Stephane Kasriel. “As a result, the array of skills employers are finding through digital platforms is growing, including technical skills like Hadoop and Kubernetes as well as non-technical skills such as taxation and urban planning.”

The top 20 fastest-growing skills:

1. US Taxation
2. Hadoop
3. Robotic process automation
4. Explainer videos
5. Computer-aided manufacturing
6. Financial planning
7. Urban design
8. Software documentation
9. Salesforce Commerce Cloud
10. Geospatial
11. Julia development
12. Kubernetes
13. Magento
14. Employee training
15. Shopify templates
16. Certified Public Accountant (CPA)
17. Vue.js framework
18. Leadership development
19. Architectural rendering
20. Podcasting