Subject-verb agreement: Basic rules

At its heart, this rule is about harmony. In English, we change the verb based on who is doing the work. Most of the time, this only happens in the "third person singular." That is a fancy way of saying he, she, it, or a single name like Sarah or The Cat. For almost every other subject, the verb stays in its basic form. If you say I eat, it's perfect. But if your friend Sarah does it, she eats. Notice that extra s? That little letter does a lot of heavy lifting in English. It signals to the listener that we are talking about one specific person or thing. It’s like a tiny flag waving to say, "Hey, this is just one person!" When you have a group, like They, the flag goes away, and we go back to eat. It is a simple system of checks and balances that ensures everyone knows exactly who is doing what.

1. 1Setting up your sentences follows a very predictable path. You can master this in three easy steps:
2. 2Identify the subject: Who is the star of your sentence? Is it I, You, We, They, or the tricky He/She/It?
3. 3Check the number: Is it one person or thing (singular), or more than one (plural)?
4. 4Match the verb:
5. 5For I, You, We, and They, use the base verb (e.g., work, play, run).
6. 6For He, She, and It, add -s or -es to the verb (e.g., works, plays, runs).
7. 7Special cases exist for verbs ending in ch, sh, s, x, or z. For these, you add -es. So, He watches TV, or She fixes the car. If the verb ends in a consonant + y, like study, you change the y to i and add -es to get studies. It’s like a small puzzle where the pieces always fit if you look at the subject first.

You will use this rule every single time you open your mouth to speak English. It is essential for describing your daily life and the world around you. Use it when you are:

• Introducing yourself or others: He lives in London.
• Ordering food: My friend wants the pizza, but I want the pasta.
• Talking about habits: The bus arrives at 9:00 AM every day.
• Stating facts: The sun rises in the east.
• Job interviews: My previous manager says I am very hardworking.

Whether you are asking for directions or telling a story about your weekend, this rule is your best friend. It provides the structure that allows people to understand you without confusion. Without it, sentences feel like a messy pile of words rather than a clear message.

While this rule is powerful, there are a few places where it takes a vacation. You don't need to worry about adding -s in these situations:

• With Modal Verbs: Words like can, must, should, and might never change. You say He can swim, not He cans swim. (Please, never say "he cans" unless you are talking about putting tomatoes in jars!)
• In the Past Tense: Most verbs in the past tense don't care about the subject. I walked and He walked are the same. The big exception is the verb to be (was/were).
• With Future Tense: When using will, the verb stays the same. I will go and She will go are identical.
• In Imperatives: When giving a command, just use the base verb. Sit down! or Eat your vegetables!

Knowing when to turn the rule off is just as important as knowing when to turn it on. It saves you from over-correcting and making your sentences sound clunky.

Even the best of us make mistakes. Here are the big ones to watch out for:

• The Missing S: This is the #1 mistake. People say He go to school instead of He goes to school. It’s a tiny sound, but your ears will start to miss it once you get used to the rule.
• The Double S: Sometimes people get excited and add an s to both the subject and the verb. The dogs barks. ✗ No! If the subject is plural (dogs), the verb is singular (bark). Think of it like a seesaw: if the s is on the noun, it shouldn't be on the verb.
• Tricky Groups: Words like Everyone, Someone, and Nobody sound like many people, but grammatically, they are singular. Everyone likes chocolate. ✓ It feels weird at first, but think of it as "every single one."
• The "Have" Trap: I have, You have, but He has. Many people say He have, which is a common slip-up. Keep an eye on has!

You might get confused between plural nouns and singular verbs because they both use the letter s.

• Noun + s = Plural (More than one thing). Example: Two books.
• Verb + s = Singular (One person doing an action). Example: She reads.

It is an inverse relationship. If your subject has an s (like The students), your verb usually does not (study). If your subject does not have an s (like The student), your verb usually does (studies). This is the "S-Switch" rule. Only one side of the partnership gets the s prize. Also, don't confuse this with the possessive 's (like John's car). That shows ownership, not action. Keep your actions and your objects in separate mental boxes!