Where se and si Sit in the Clitic Chain

Czech packs all its little unstressed words — the past and conditional auxiliaries, the reflexive se/si, and short object pronouns — into a single cluster that sits in second position in the clause. Inside that cluster the words line up in a fixed order that has nothing to do with English word order. This page pins down exactly where se and si go in the chain: they come right after the auxiliary and before every object pronoun. Once you know the slots, you can assemble any clause mechanically.

The second-position rule, in one line

Before we order the cluster, recall the law that governs the whole thing: the clitic cluster goes immediately after the first stressed unit of the clause — the first word or phrase. See the second-position clitic rule for the full picture. Everything below concerns the internal order once you know the cluster sits in slot two.

The fixed order of the cluster

The clitics fall into numbered slots. They always appear in this sequence, and you simply skip any slot you don't need:

So the skeleton is: AUX → SE/SI → DATIVE → ACCUSATIVE. The reflexive sits in the second slot, glued right behind the auxiliary and in front of any object pronoun. This never varies.

Building the chain one slot at a time

Let's grow a clause from a single clitic up to a four-member chain so the sequence becomes visible.

One member — just the reflexive:

Two members — auxiliary + reflexive. With the past tense, the auxiliary jsem comes first, then si:

Here the order is jsem (aux) → si (refl) → to (acc) — auxiliary, then reflexive, then the object. Try it the English way and you get nonsense.

Three members — auxiliary + reflexive + dative:

The chain is jsem (aux) → se (refl) → mu (dat). Note that the subject pronoun Já is the first unit; the whole cluster lands right after it, in second position.

Four members — auxiliary + reflexive + dative + accusative:

Order: bych (aux) → si (refl) → je (acc) — and if a dative were present it would slot between si and je. Here is a clean four-slot example:

That is jsem (aux) → si (refl) → je (acc): auxiliary, reflexive, object.

That is by (aux) → mi (dat) → to (acc): no reflexive here, so slot 2 is simply empty and the dative follows the auxiliary directly.

The fusion forms: ses and sis

There is one irregularity you must know. In the past tense, second-person singular, the auxiliary is jsi. When jsi meets the reflexive se or si, they fuse into a single word:

• se + jsi → ses
• si + jsi → sis

So you do not say se jsi or si jsi; you say ses and sis. This is obligatory in the standard language.

Comparison with English

English keeps its pronouns next to the verb they belong to and lets them spread across the clause in roughly the order of meaning: "I bought it for myself yesterday." Czech does the opposite — it rips all the unstressed words out of their phrases and stacks them in one cluster in second position, in a grammatically fixed order that ignores meaning. English has nothing like the auxiliary–reflexive–dative–accusative template, and nothing like the obligatory ses/sis fusion. The single most useful habit is this: do not place these words one at a time as you would in English. Identify the first unit of the clause, then drop the entire assembled cluster — in AUX–SE/SI–DAT–ACC order — right after it.

Common Mistakes

Key Takeaways

• The cluster order is fixed: auxiliary → se/si → dative → accusative.
• se and si sit immediately after the auxiliary and before every object pronoun.
• The whole chain still obeys the second-position rule — it lands right after the first unit of the clause.
• In the 2nd-person singular past, se + jsi = ses and si + jsi = sis (obligatory fusion).
• Build the cluster as one block with the template bych–se–mi–ho; never place the words one-by-one in English order.