Interview experience
Deloitte Interview Questions and Answers (2026)
Overview
Section titled “Overview”Deloitte USI (the technology delivery arm most CS graduates interview into) runs a 3-5 stage process anchored by an aptitude-plus-coding OA, one or two technical interviews, and a closing managerial/HR round.
Deloitte interview process at a glance
Section titled “Deloitte interview process at a glance”| Round | Duration | What they test |
|---|---|---|
| Online Aptitude Test | 60-90 min | Quant, logical, verbal, technical MCQs, 1 SQL query, 1 easy coding problem |
| Group Discussion (if conducted) | 20-30 min | Current affairs / business topic |
| Technical Interview(s) | 30-45 min each | Resume/project depth, 1 easy DSA question, SQL, OOPs/DBMS |
| Managerial / HR Interview | 20-30 min | Communication, client readiness, fit |
Online Aptitude Test
Section titled “Online Aptitude Test”A single online paper that filters on quant, logical, and verbal aptitude, then layers on technical MCQs, one SQL query, and one easy-medium coding problem. Some drives pair this with a Versant test to screen spoken/written English fluency, since USI roles are client-facing.
Common questions
- Time-speed-distance, percentages, and profit-loss quant problems
- Logical reasoning puzzles and data sufficiency
- One easy-medium coding problem - array/string manipulation, LeetCode-style
- A SQL query question involving joins or aggregation
- Versant-style reading-aloud and sentence-repeat tasks (where conducted)
Group Discussion (if conducted)
Section titled “Group Discussion (if conducted)”Not every drive runs a GD, but where it does, it’s a 15-20 minute discussion in groups of 6-8 on a current-affairs or business topic, judged on structured articulation and listening rather than dominating the conversation.
Common questions
- Impact of AI/automation on traditional consulting work
- Digital transformation in Indian businesses
- Remote work vs office culture - trade-offs
- A current-affairs topic tied to technology or business
Round-by-round breakdowns are on the Deloitte interview experience page.
Technical Interview(s)
Section titled “Technical Interview(s)”Opens with a detailed walkthrough of your strongest resume project - interviewers push on stack choices, the hardest bug you hit, and what you’d rebuild - then moves into one easy DSA problem, SQL joins/aggregations (GROUP BY, window functions), and OOPs/DBMS fundamentals.
Common questions
- Walk through your project’s architecture, your specific contribution, and the hardest bug you debugged
- One easy array/string problem - approach via two pointers or hashing, then complexity
- Write a SQL query using joins and GROUP BY; explain a window function
- Explain OOPs concepts (inheritance, polymorphism) with a class design example (ATM/library system)
- DBMS normalization and constraints
Managerial / HR Interview
Section titled “Managerial / HR Interview”The closing stage, sometimes split into a separate managerial round and HR round, sometimes merged. It checks motivation for consulting, client-facing readiness, and a couple of behavioural stories.
Common questions
- Why consulting, and why Deloitte specifically?
- Describe a client-facing or communication example
- Walk me through how you structured a complex problem under time pressure
- Tell me about a time you had to maintain integrity or push back on something you disagreed with
- Are you comfortable with the notice period / relocation Deloitte USI expects?
Sample answer frameworks for each of these are on the Deloitte HR interview questions page.
Audit/Tax vs Technology/USI: why the track matters
Section titled “Audit/Tax vs Technology/USI: why the track matters”Deloitte hires across genuinely different business lines - Audit & Assurance, Tax, Consulting/Advisory, and Technology (USI, the US-India delivery centers doing actual software development, data, and cloud work). This page describes the Technology/USI track, which is what most CS/IT campus hires go through: an OA with a coding and SQL component, technical interviews with a DSA question, and a managerial/HR close. Audit and Tax hiring, aimed largely at commerce and accounting graduates, is a lighter process built around aptitude, group discussion, and HR, with little to no coding. Check which business line your offer letter or registration email names before you prep.
Common technical interview questions and answers
Section titled “Common technical interview questions and answers”Q: Write a SQL query using joins and GROUP BY to find each department’s average salary.
A correct answer is SELECT d.dept_name, AVG(e.salary) AS avg_salary, COUNT(*) AS headcount FROM employees e JOIN departments d ON e.dept_id = d.dept_id GROUP BY d.dept_name HAVING COUNT(*) > 5 ORDER BY avg_salary DESC; The points interviewers check are that every non-aggregated column in the SELECT list also appears in GROUP BY, that filters on aggregates belong in HAVING while filters on individual rows belong in WHERE, and that WHERE runs before grouping so it is the cheaper place to filter. Mention that AVG silently ignores NULL salaries, which can skew the result.
Q: What is a window function and how does it differ from GROUP BY?
A window function computes a value over a set of rows related to the current row while keeping every row in the output; GROUP BY collapses rows into one row per group. For example SELECT emp_name, dept_id, salary, RANK() OVER (PARTITION BY dept_id ORDER BY salary DESC) AS rnk FROM employees; returns every employee alongside their rank within their department. The common functions are ROW_NUMBER (always unique), RANK (ties share a rank and leave gaps), DENSE_RANK (ties share a rank with no gaps), and LAG/LEAD for comparing against the previous or next row. Window functions are evaluated after WHERE and GROUP BY, so filtering on one requires wrapping it in a subquery or CTE.
Q: When do you use two pointers versus hashing on an array problem?
Two pointers works when the data is sorted or can be sorted and gives O(1) extra space - for a sorted two-sum you move the left pointer right when the sum is too small and the right pointer left when it is too large, which is O(n) after an O(n log n) sort. Hashing works on unsorted data and gives O(n) time for O(n) space by remembering values or counts already seen. The choice comes down to whether the interviewer cares more about memory or about preserving the original order and indices. State both options and the trade-off before writing code - Deloitte panels weight the approach explanation as heavily as the code.
Q: Explain inheritance and polymorphism with a class design example.
Inheritance lets a subclass reuse and extend a base class - an Account base class with balance, deposit, and withdraw, extended by SavingsAccount and CurrentAccount that override withdraw to apply different overdraft rules. Polymorphism means calling withdraw through an Account reference runs the subclass version, chosen at runtime via the virtual dispatch table, so an ATM class can process any account type without knowing its concrete class. Compile-time polymorphism is method overloading, resolved by signature; runtime polymorphism is overriding. The payoff is that adding a new account type needs no change to the ATM code - the Open-Closed Principle in practice.
Q: How would you design classes for a library management system?
Start with the entities: Book (ISBN, title, author), BookCopy (copy_id, ISBN, status) kept separate from Book because five physical copies share one title, Member, and Loan (copy_id, member_id, issue_date, due_date, return_date). Behaviour lives on a Library service class handling issue, return, and fine calculation, with an abstract Member base class subclassed by StudentMember and FacultyMember that override maxBooksAllowed and loanPeriodDays. Keep fine calculation in its own FinePolicy class so the rule can change without touching Loan. Interviewers mainly check that you separate the title from the physical copy - conflating the two is the most common mistake.
Q: What is the difference between a primary key, a unique key, and a foreign key?
A primary key uniquely identifies each row, cannot be NULL, and there is exactly one per table; it typically defines the clustered index. A unique key also enforces uniqueness but permits NULLs (one in SQL Server, several in most other engines), and a table may have many. A foreign key is a column referencing a primary or unique key in another table, enforcing referential integrity so you cannot insert an order for a customer who does not exist. Foreign keys also drive ON DELETE CASCADE, SET NULL, or RESTRICT behaviour - the follow-up most candidates miss.
Q: How do you reverse the words in a sentence in place?
The standard trick is a double reversal: reverse the entire character array first, then reverse each individual word delimited by spaces. Reversing “the sky is blue” gives “eulb si yks eht”, and reversing each word within that yields “blue is sky the”. This is O(n) time and O(1) extra space when the string is mutable, which is the version interviewers are looking for. If the language has immutable strings, the pragmatic alternative is splitting on whitespace, reversing the token list, and joining, at O(n) space - say which one you are using and why.
Q: What is the difference between DELETE, TRUNCATE, and DROP?
DELETE is a DML statement that removes rows one at a time subject to a WHERE clause, fires row triggers, is fully logged, and can be rolled back. TRUNCATE is DDL that deallocates the table’s data pages wholesale, so it is far faster, resets identity counters, does not fire row triggers, and cannot be filtered with WHERE. DROP removes the table structure, its indexes, and its permissions entirely. In most engines TRUNCATE and DROP cause an implicit commit, and TRUNCATE is blocked outright when another table holds a foreign key referencing this one.
Frequently asked questions about Deloitte interviews
Section titled “Frequently asked questions about Deloitte interviews”What is the Deloitte interview process for freshers?
Deloitte USI (the US-India technology delivery arm most CS graduates join) typically runs 3-4 stages: 1. Online Aptitude Test - quant, logical, verbal, plus technical MCQs, one SQL query, and one easy coding problem, sometimes paired with a Versant English-fluency test. 2. Group discussion at some colleges. 3. One or two Technical Interviews (30-45 min) on your resume project, SQL, an easy DSA question, and CS fundamentals (OOPs, DBMS). 4. A Managerial/HR round on fit, ownership, and client-readiness. Total timeline: 1-3 weeks, sometimes stretching to months for offer approval.
What questions are asked in Deloitte interviews?
The OA mixes aptitude with technical MCQs, one SQL query, and one easy-medium coding problem (arrays/strings, LeetCode-style). Technical interviews open with a deep resume/project walkthrough, then move to one easy DSA question, SQL joins and aggregations, and OOPs/DBMS fundamentals. The Managerial/HR round checks client-readiness, teamwork, and why Deloitte.
How many rounds are there in the Deloitte interview?
Deloitte USI typically runs an Online Aptitude Test, an optional Group Discussion, one or two Technical Interviews, and a closing Managerial/HR round - so 3-5 touchpoints depending on the drive. Some reports describe it as simply “2 rounds: Technical + Managerial” or “3 rounds: two Technical + one Managerial” once the OA is cleared.
How should I prepare for Deloitte interviews?
Practise timed aptitude plus one easy-medium DSA problem a day, get comfortable writing SQL joins and aggregate queries under time pressure, and revise OOPs/DBMS fundamentals. Prepare one crisp project narrative you can defend in depth - Deloitte panels probe implementation choices, not just outcomes. Use STAR for the Managerial/HR round.
What is Deloitte USI, and is the interview different from Audit or Tax roles?
Deloitte USI (US-India offices) is the technology and consulting delivery arm that most CS/IT campus hires join, and it’s what this page’s process describes - OA with a coding/SQL component, technical interviews, and a managerial/HR round. Deloitte’s core Audit, Tax, and Assurance hiring runs a lighter, largely non-coding process built around aptitude, group discussion, and HR - built for commerce/accounting graduates rather than CS ones.
Is there a coding round in Deloitte interviews?
Yes, for Technology/USI roles. The OA usually includes one easy-medium coding problem alongside aptitude and a SQL query, and the technical interview follows up with one more easy DSA question plus deeper SQL and CS-fundamentals questions. It’s not a DSA-heavy loop like a pure product company, but it isn’t skippable either.