Show your work: why RebaseNest never gives you a single number

✍️ RebaseNest Team · Last updated 8 May 2026

·8 min read
philosophyreturneenritaxtoolstransparency

Educational only. Not investment, tax, legal, or immigration advice. RebaseNest is not a registered investment adviser under SEBI, SEC, or FCA. Indian tax, FEMA, and DTAA rules change frequently. Verify every threshold and citation with a qualified cross-border CA before acting. Full disclaimer.

Assuming you are in your late 30s on H1B or working in London, you have spent an hour with three different "NRI tax calculators" and walked away with three different numbers. None of them showed you the formula. None of them told you which DTAA article they used, which regime under section 115BAC they assumed, or whether they treated the year of return as RNOR or ROR. You are now less certain than when you started.

That is the gap RebaseNest is trying to close. Every output the site prints has its assumptions visible, links to the source rule, and ends with "confirm with a CA." This article is the philosophy behind that, written so you can decide whether the trade-off is worth it for you.

1. Why a single number is the wrong unit

Cross-border tax math is not one calculation. It is a chain of choices, and the answer at the end depends on which branch you took at each step.

Step                          Choice you have to make
Residential status (year 1)   Resident / RNOR / NR per ITA s.6 day-count
Residential status (FEMA)     Independent of tax, drives bank-account redesignation
Tax regime                    Old (deductions allowed) vs new under s.115BAC
DTAA application              Treaty resident under Article 4 tie-breaker?
Foreign income treatment      Taxable in India only if residential status pulls it in
Foreign tax credit            Claim under s.90 + Rule 128 + Form 67
RSU and capital gains         Source country, holding period, step-up reset rules

A single-number calculator picks one branch at every step and shows you the leaf. That is fine if the branches it picked match your facts. The problem is you cannot tell. Two calculators showing different numbers usually means they took different branches, not that one is wrong.

The unit that actually helps is a range plus the levers. "Your year-1 India tax sits between X and Y depending on whether you trigger ROR before March 31 and whether you elect the new regime." Now you can see what to ask the CA.

2. What "show your work" means in practice

Every page on RebaseNest that prints a number has three sections beneath it:

  • Assumptions used. The full input set the answer depends on, including defaults you did not type in (e.g. "assumed RNOR for FY25-26 because day count under section 6(6) sits below the threshold given the prior 4 years").
  • Formula or rule applied. The arithmetic, with the section number it comes from.
  • Source link. A live link to the IndiaCode bitstream PDF for the ITA or FEMA, or to the RBI Master Direction, or to the relevant DTAA article on the Income-tax Department site.

The point is not to be exhaustive. The point is that you can audit any step, and so can a CA you forward the page to. The calculator becomes a conversation starter, not a black box.

3. The citation stack we hold ourselves to

These are the canonical sources every numerical claim on the site has to land on. They are not interchangeable.

Topic                          Canonical source
Scope of total income          Income-tax Act 1961 s.5
Residence (tax)                Income-tax Act 1961 s.6
RNOR status                    Income-tax Act 1961 s.6(6)
Residence (FEMA)               FEMA 1999 s.2(v); RBI FED MD 14/2015-16
NRE / NRO / FCNR accounts      RBI Master Direction FED MD 14/2015-16
FTC mechanics                  ITA s.90 + Income-tax Rules 1962 Rule 128 + Form 67
DTAA tie-breaker               India-USA / India-UK DTAA Article 4
Treaty relief (India-USA)      India-USA DTAA Article 25
Treaty relief (India-UK)       India-UK DTAA Article 24
FCNR-type interest             ITA s.10(15)(iv)(fa) (interest paid by a scheduled
                               bank to a non-resident or RNOR on qualifying
                               foreign-currency deposits, subject to conditions)
PPF eligibility                Public Provident Fund Scheme 2019
US side reporting              FBAR (FinCEN Form 114), FATCA Form 8938

If a number on the site cannot be tied back to one of these, it does not ship. That is also why several "common calculators" you see on Reddit threads cannot be reproduced here, because they cite blog posts, not statute.

4. Why "confirm with a CA" is not a cop-out

Every output ends with the same line, and people sometimes read it as the tool dodging responsibility. It is the opposite. RebaseNest is not a SEBI-registered investment adviser, an enrolled tax practitioner, or a chartered accountant. None of those credentials sit behind the site. The line is doing two real jobs:

  • Legal. RebaseNest avoids personalised recommendations and does not hold itself out as registered investment advice. The SEBI (Investment Advisers) Regulations, 2013 govern that line. The site stays on the educational side of it on purpose.
  • Practical. Your year-1 India return depends on date-stamped facts (entry date, RSU vest dates, account redesignation date) that change the answer. A CA who sees the full picture will catch things a general tool cannot. The output is the input to that conversation, not the substitute for it.

To each on their own. If you have a simple year (clean RNOR, no RSU mess, no rental, no foreign-account complications) the site's outputs may already match what your CA would say, and the cost of confirming is small. If you have a complicated year, the site is at best a checklist of questions. Either way, the line stays.

5. What this means for you, the user

A few practical implications if you actually use the tools.

What you do                            What you should expect from RN
Enter your year-1 dates                Range, not a point. Both branches priced.
Click "show working"                   Full input set + formula + source PDF link.
Disagree with an assumption            Toggle it, the number recomputes, the formula stays visible.
Forward output to your CA              They can audit every step in under 10 minutes.
Ask for a "what to do" recommendation  You will not get one. The tool surfaces options, not picks.

The friction is real. A single-number calculator feels faster, especially the first time. The bet RebaseNest is making is that within two or three uses you will prefer the version where the working is visible, because the cost of acting on a hidden assumption that did not match your case is higher than the cost of reading a paragraph of "here is why this number, here is the section."

6. The trade-off, named

Some people will want a number, fast, and will use a tool that gives them one. That is a fair choice. The cost shows up later, when an assumption that was never visible turns out to be wrong for your case and you have already filed.

The other path is slower up front and more transparent. You read the formula. You click through to the section. You see which lever moves the answer. You take the page to a CA and the conversation starts at the right place. That is the path the site is built for.

Neither path is wrong. They optimise for different things. RebaseNest is the second one, by design, and this article exists so you know what you are signing up for before you click "calculate."

A note on what this is. This is a general educational note on how RebaseNest approaches transparent calculation design, not personalised advice. Numbers age. Rules change. The only person who can sign off on your specific case is a qualified cross-border chartered accountant looking at your full facts. Use this as a checklist of questions to take to that conversation, not as the answer.

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